feat: Trusted Auctioneer: Clear mempool when mempool state is reset

[bharath-123]

Whenever we create a new Optimistic block, we throw an event which is being listened for in the txpool maintenance loop. When we receive a new optimistic block, we update the state of the pool to point the head block and state to the new optimistic block.
The trusted auctioneer also clears the pending and queued transactions in the mempool when the pool state is updated. We do this to validate that only transactions who can pay their priority fees based on the stateful validations are sent to the trusted auctioneer.

Changes made:

1. Add a ClearList method to the list struct which clears the transaction list.
2. Add a method for clearPendingAndQueued to the LegacyPool struct which clears the pending and queued transactions.
3. We remove transaction promotion during a reset as we are anyways clearing the mempool.