Fallback to using the bridging user (Gitter badger) when we fail to delete a message from the Gitter user
As a Gitter admin, we fail to actually delete the message on Matrix if it's from a non-gitter.im
homeserver user. This is because we can't act as the federated Matrix user who sent the event and the Gitter admin doesn't have power levels in the Matrix room.
If we see the Matrix redaction fail from the user, we should also try from the bridging user (Gitter badger).