txpool: don't maintain the pool during major sync (#13004)

* txpool: don't maintain the pool during major sync

Fix shall prevent from wasting the CPU during the major sync. No actions
are actually required in transaction pool during the major sync.

Fixes: #12903

* passing sync_oracle to maintain method

* fixed: builder, txpool tests

* do not maintain tx-pool if node gone out of sync

* EnactmentAction: all logic moved to EnactmentState

Tests to be done.

* maintain guard logic moved directly to MaintainedTransactionPool

* minor fixes

* EnactmentAction: all logic moved to EnactmentState (again)

* SyncOracle fixes here and there

* Update client/transaction-pool/src/enactment_state.rs

Co-authored-by: Bastian Köcher <[email protected]>

* Update client/transaction-pool/src/enactment_state.rs

Co-authored-by: Bastian Köcher <[email protected]>

* sync_oracle removed

* spelling + fmt + doc

* Review suggestions applied

* log::info -> debug

* Update client/transaction-pool/src/enactment_state.rs

Co-authored-by: Bastian Köcher <[email protected]>

* ".git/.scripts/commands/fmt/fmt.sh"

Co-authored-by: parity-processbot <>
Co-authored-by: Bastian Köcher <[email protected]>