Disable the `union` test in read-only Mongo.
Disable the `union` test in read-only Mongo.

jedesah/Quasar,slamdata/quasar,slamdata/slamengine,quasar-analytics/quasar,jedesah/Quasar,slamdata/slamengine,quasar-analytics/quasar,drostron/quasar,djspiewak/quasar,jedesah/Quasar,quasar-analytics/quasar,drostron/quasar,jedesah/Quasar,quasar-analytics/quasar,slamdata/slamengine,drostron/quasar,drostron/quasar