sql,metrics: ROLLBACK after RELEASE cockroach_restart misclassified in metrics

[nvanbenschoten]

BEGIN; SAVEPOINT cockroach_restart; ...; RELEASE SAVEPOINT cockroach_restart; ROLLBACK; currently increments the following four metrics:

sql.txn.begin.count
sql.restart_savepoint.count
sql.restart_savepoint.release.count
sql.txn.rollback.count

This last metric is incorrect. We should be incrementing the sql.txn.commit.count metric instead, because the transaction has committed.

The fix for this will be to update StatementCounters.incrementCount with condition logic in the tree.RollbackTransaction case that consults the session's state.

[knz]

@solongordon can you triage this?