Manually handle locking and unlocking to prevent race conditions
if the fee logic. The case that needs to be handled is as follows:
a `gas-oracle` transaction updates the gas price after an queue
origin sequencer tx is sent via RPC and already goes through the
fee check. This would cause the transaction to be accepted and then
fail during the state transition. This is bad because we do not
have logic to hold on to the failed transaction to execute later,
which is what the user would expect when sending transactions to
L1. All transactions that are sent to the miner *must* be valid
transactions.