Don't report stats in LogicalRepApplyLoop() when in xact.

Don't report stats in LogicalRepApplyLoop() when in xact.

pgstat_report_stat() is only supposed to be called outside of transactions. In
5891c7a8ed8 I added a pgstat_report_stat() call into LogicalRepApplyLoop()'s
timeout branch. While not commonly reached inside a transaction, it is
reachable (e.g. due to network bottlenecks or the sender being stalled / slow
for some reason).

To fix, add a !IsTransactionState() check.

No test added because there's no easy way to reproduce this case without
patching the code.

Reported-By: Erik Rijkers <er@xs4all.nl>
Discussion: https://postgr.es/m/b3463b8c-2328-dcac-0136-af95715493c1@xs4all.nl