executor/mars: re-register runners that changed description
Ensure that the gitlab runner's description matches the MaRS's computed full name.
This fixes the case where $farm-$basename-1
gets deleted, which ends
up renaming $farm-$basename-2
into $farm-$basename-1
in MaRS but
not in gitlab... which could lead to errors such as:
ERROR: Could not queue the job: "Unknown machine with ID keywords-gfx10-navi10-3"