Disable txpool when not in sync

[fab-10]

PR description

With this PR the transaction pool factory is now aware if Besu is in sync or not, using the events triggered by the SyncState, and will disable the txpool as soon as the node is out of sync, so avoiding validating txs while not necessary.
This PR also implements a better way to process the onBlockAdded event in the txpool, avoiding the possibility of a tight loop that could result in high cpu usage.

Fixed Issue(s)

fixes #6001

[github-actions]

• I thought about documentation and added the doc-change-required label to this PR if updates are required.
• I thought about the changelog and included a changelog update if required.
• If my PR includes database changes (e.g. KeyValueSegmentIdentifier) I have thought about compatibility and performed forwards and backwards compatibility tests

[ahamlat]

@fab-10 I tested on a mainnet forest archive sync'ing node, and it worked. I don't see anymore the validation of remote transactions. I see the deactivation in the logs :

{"@timestamp":"2024-01-02T08:52:02,252","level":"INFO","thread":"nioEventLoopGroup-3-6","class":"TransactionPoolFactory","message":"Node out of sync, disabling transaction handling","throwable":""}

I also confirmed by checking the metrics :

However, I still see that we are announcing new transactions hashes :

[fab-10]

@ahamlat about

I still see that we are announcing new transactions hashes

what you see are the incoming messages that we still receive, but are just ignored and not processed, you should check the outbound panel to verify that we are not sending them.

[ahamlat]

Right, I was looking to the inbound messages. When checking outbound messages on the transaction pool, we can see that we have no traffic, which validates this PR.