remove getter from babe pallet (#4912)

### ISSUE
Link to the issue:
https://github.com/paritytech/polkadot-sdk/issues/3326
cc @muraca 

Deliverables
 - [Deprecation] remove pallet::getter usage from all pallet-babe

### Test Outcomes
___
Successful tests by running `cargo test -p pallet-babe --features
runtime-benchmarks`


running 32 tests
test
mock::__pallet_staking_reward_curve_test_module::reward_curve_piece_count
... ok
test mock::__construct_runtime_integrity_test::runtime_integrity_tests
... ok
test mock::test_genesis_config_builds ... ok
2024-06-28T17:02:11.158812Z ERROR runtime::storage: Corrupted state at
`0x1cb6f36e027abb2091cfb5110ab5087f9aab0a5b63b359512deee557c9f4cf63`:
Error { cause: Some(Error { cause: None, desc: "Could not decode
`NextConfigDescriptor`, variant doesn't exist" }), desc: "Could not
decode `Option::Some(T)`" }
2024-06-28T17:02:11.159752Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::add_epoch_configurations_migration_works ... ok
test tests::author_vrf_output_for_secondary_vrf ... ok
test benchmarking::bench_check_equivocation_proof ... ok
2024-06-28T17:02:11.160537Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::can_estimate_current_epoch_progress ... ok
test tests::author_vrf_output_for_primary ... ok
test tests::authority_index ... ok
2024-06-28T17:02:11.162327Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::empty_randomness_is_correct ... ok
test tests::check_module ... ok
2024-06-28T17:02:11.163492Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::current_slot_is_processed_on_initialization ... ok
test tests::can_enact_next_config ... ok
2024-06-28T17:02:11.164987Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.165007Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::can_predict_next_epoch_change ... ok
test tests::first_block_epoch_zero_start ... ok
test tests::initial_values ... ok
2024-06-28T17:02:11.168430Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.168685Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.170982Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.171220Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::only_root_can_enact_config_change ... ok
test tests::no_author_vrf_output_for_secondary_plain ... ok
test tests::can_fetch_current_and_next_epoch_data ... ok
2024-06-28T17:02:11.172960Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::report_equivocation_has_valid_weight ... ok
2024-06-28T17:02:11.173873Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.177084Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::report_equivocation_after_skipped_epochs_works ...
2024-06-28T17:02:11.177694Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.177703Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.177925Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.177927Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
ok
2024-06-28T17:02:11.179678Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.181446Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.183665Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.183874Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.185732Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.185951Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.189332Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.189559Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.189587Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::generate_equivocation_report_blob ... ok
test tests::disabled_validators_cannot_author_blocks - should panic ...
ok
2024-06-28T17:02:11.190552Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.192279Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.194735Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.196136Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.197240Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::skipping_over_epochs_works ... ok
2024-06-28T17:02:11.202783Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.202846Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.203029Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.205242Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::tracks_block_numbers_when_current_and_previous_epoch_started
... ok
2024-06-28T17:02:11.208965Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::report_equivocation_current_session_works ... ok
test tests::report_equivocation_invalid_key_owner_proof ... ok
2024-06-28T17:02:11.216431Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
2024-06-28T17:02:11.216855Z ERROR runtime::timestamp:
`pallet_timestamp::UnixTime::now` is called at genesis, invalid value
returned: 0
test tests::report_equivocation_validate_unsigned_prevents_duplicates
... ok
test tests::report_equivocation_invalid_equivocation_proof ... ok
test tests::valid_equivocation_reports_dont_pay_fees ... ok
test tests::report_equivocation_old_session_works ... ok
test
mock::__pallet_staking_reward_curve_test_module::reward_curve_precision
... ok

test result: ok. 32 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.20s

   Doc-tests pallet-babe

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.00s

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