Fix art #3241 Abusive Gerrit cache flushing

Only flush caches that correspond to the tables we actually modify
Merge commit 'refs/changes/14/414/1' of http://gerrit.tuleap.net/tuleap into stable

* http://gerrit.tuleap.net/tuleap:
  Fix art #3241 Abusive Gerrit cache flushing
This is Tuleap 5.12.99.63