Fixes issue #24849 make relevant methods synchronized in LocalTxConnectionEventListener

[escay]

Make relevant methods synchronized in LocalTxConnectionEventListener and protect associatedHandles from external clear calls.

I first tried to move most of the ConnectorXAResource.resetAssociation method inside a synchronous method in the LocalTxConnectionEventListener, but that also meant two other methods from ConnectorXAResource needed to be refactored and moved into LocalTxConnectionEventListener. So I undid that and chose for cloning the map and returning a clone to make the method getAssociatedHandles thread safe. This is a different solution as used in the Payara fix I mention in the issue. But I think it is better to leave the association and disassociating of ManagedConnection logic inside the ConnectorXAResource code.

I did not add multi threading unit tests, since only the basic synchronized(this) approach is used to protect the associatedHandles map. No need to test java. I did add some basic unit test logic for the add and remove logic used by ConnectorXAResource.

[avpinchuk]

Also, because synchronized is only used to guard access to the associated handles map, maybe it's better to use ReentrantReadWriteLock instead?

[escay]

Also, because synchronized is only used to guard access to the associated handles map, maybe it's better to use ReentrantReadWriteLock instead?

I cannot oversee the impact of using ReentrantReadWriteLock on only the associatedHandles. Some code like the
poolManager.resourceClosed(handle); calls could also be affected by the synchronized approach. I have no easy way to test this, I know the synchronized version works for me for the last years in Payara: payara/Payara@c09e8aa to avoid the exception, so I tried to stay near that solution.

To know for sure I think I need to have found the real cause of issue #24805 and probably also of issue #23483 which I think could be related and run my test set many times.
I am also looking at "dataStructure" get and remove logic in:

https://github.com/eclipse-ee4j/glassfish/blob/3e5203c56e63abf68cece6ddc76cf9ffd91c3d69/appserver/connectors/connectors-runtime/src/main/java/com/sun/enterprise/resource/pool/ConnectionPool.java#L679C1-L682C66

where I suspect resourceHandles can get mixed up, and could perhaps cause this issue as side effect.