ChangeInserter: always commit ChangeUpdate

ChangeUpdate.commit() is by design a no-op if no updates were made to
the change, so no need to check before calling.

Change-Id: Ic7b657553e28c2f0ce81d48e06e0a9c9d430a0d9

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeInserter.java

@@ -191,9 +191,7 @@ public class ChangeInserter {
     } finally {
       db.rollback();
     }
-    if (messageIsForChange()) {
     update.commit();
-    }
     CheckedFuture<?, IOException> f = mergeabilityChecker.newCheck()
         .addChange(change)
         .reindex()