Generate tick entry ids and only register ticks as the last_id expected by the bank. Since the bank is MT, the in-flight pipeline of transactions cannot be close to the end of the queue or there is a high possibility that a starved thread will encode an expired last_id into the ledger. The banking_stage therefore uses a shorter age limit for encoded last_ids then the validators.
Bench client doesn't send transactions that are older then 30 seconds.