test GDS broadcast redundancy on dmt1 and dmt2

assigned to @jonathan-hanks

added priority label

added LHO label

mentioned in issue #32 (closed)

work permit for the test: https://services2.ligo-la.caltech.edu/LHO/workpermits/view.php?permit_id=11113

mentioned in issue #51 (closed)

This was done and the failover succeeded, which was great. Data kept flowing and no errors were reported (although I think we want some kind of notification (see #51 (closed))).

closed