No parameter estimation for mock events uploaded to gracedb.ligo.org.

Currently, all of the events including mock events uploaded to gracedb.ligo.org are followed up by the PE with the "production" setting, which take ~days. Since mock events are uploaded frequently, the PE runs pile up and exploit computational resources, preventing the PE runs on real events and playground events. This patch prevents PE runs from being started for mock events uploaded to gracedb.ligo.org. Note that the PE workflow is being tested with mock events uploaded to gracedb-playground.ligo.org.