TransactionServerChannel need to include in-flight transactions when handling xa txn recovery.

See JBEAP-8635 comments for more details on this:
"XAResource::recover() method on server1 (the client in this case) was invoked by the recovery manager - it should propagate to server2 and that would return the aggregate of the following two operations:
Set<Xid> toReturn = ((TransactionImporterImple) SubordinationManager.getTransactionImporter()).getInflightXids(parentNodeName);
Xid[] doRecover = ((XATerminatorImple) SubordinationManager.getXATerminator()).doRecover(null, parentNodeName);

This can also be done by calling this single SPI method:
https://github.com/jbosstm/jboss-transaction-spi/blob/master/src/main/java/org/jboss/tm/ExtendedJBossXATerminator.java#L112"