sfaci, xxblackburnxx, catrope: Backport for [[gerrit:1285412|Remove `wgTestKitchenExperimentStreamNames` (T422358)]], [[gerrit:1295531|Enable AbuseFilter block action on nlwiki (T427384)]] synced to the testservers (see https://wikitech.wikimedia.org/wiki/Mwdebug). Changes can now be verified there.