remove getter from vesting pallet (#4902)

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

cc @muraca 

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

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

running 45 tests
test benchmarking::bench_force_vested_transfer ... ok
test benchmarking::bench_vest_other_locked ... ok
test mock::__construct_runtime_integrity_test::runtime_integrity_tests
... ok
test benchmarking::bench_not_unlocking_merge_schedules ... ok
test benchmarking::bench_unlocking_merge_schedules ... ok
test mock::test_genesis_config_builds ... ok
test tests::build_genesis_has_storage_version_v1 ... ok
test tests::check_vesting_status ... ok
test benchmarking::bench_force_remove_vesting_schedule ... ok
test tests::check_vesting_status_for_multi_schedule_account ... ok
test benchmarking::bench_vest_locked ... ok
test tests::extra_balance_should_transfer ... ok
test tests::generates_multiple_schedules_from_genesis_config ... ok
test tests::force_vested_transfer_allows_max_schedules ... ok
test tests::force_vested_transfer_correctly_fails ... ok
test tests::force_vested_transfer_works ... ok
test tests::liquid_funds_should_transfer_with_delayed_vesting ... ok
test tests::merge_finished_and_ongoing_schedules ... ok
test benchmarking::bench_vest_unlocked ... ok
test tests::merge_finished_and_yet_to_be_started_schedules ... ok
test tests::merge_finishing_schedules_does_not_create_a_new_one ... ok
test tests::merge_ongoing_and_yet_to_be_started_schedules ... ok
test benchmarking::bench_vest_other_unlocked ... ok
test tests::merge_ongoing_schedules ... ok
test tests::merge_schedules_that_have_not_started ... ok
test tests::merge_vesting_handles_per_block_0 ... ok
test tests::per_block_works ... ok
test tests::merge_schedules_throws_proper_errors ... ok
test tests::multiple_schedules_from_genesis_config_errors - should panic
... ok
test tests::merging_shifts_other_schedules_index ... ok
test tests::non_vested_cannot_vest_other ... ok
test tests::unvested_balance_should_not_transfer ... ok
test tests::non_vested_cannot_vest ... ok
test tests::vested_balance_should_transfer ... ok
test tests::remove_vesting_schedule ... ok
test tests::vested_transfer_correctly_fails ... ok
test tests::vested_balance_should_transfer_with_multi_sched ... ok
test tests::vested_balance_should_transfer_using_vest_other ... ok
test tests::vested_transfer_less_than_existential_deposit_fails ... ok
test tests::vesting_info_ending_block_as_balance_works ... ok
test tests::vesting_info_validate_works ... ok
test
tests::vested_balance_should_transfer_using_vest_other_with_multi_sched
... ok
test tests::vested_transfer_works ... ok
test tests::vested_transfer_allows_max_schedules ... ok
test benchmarking::bench_vested_transfer ... ok

test result: ok. 45 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.10s

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