SubordinateAtomicAction invokes the beforeCompletion syncs from doPrepare and doOnePhaseCommit, even when the tx is in state ABORT_ONLY.

Whilst outside the scope of the JTA or JCA specs, this is inconsistent with the standard JTA behaviour of running beforeCompletion only prior to commit attempts, not rollbacks.

Make a best effort check to avoid the overhead of running the syncs for cases where we know we can't commit.