I've been watching beta since we've started committing to git for every
deployment, and it seems that the git directory gets out-of-hand pretty
quickly. Leaving loose objects laying around when we flatten the
/srv/mediawiki directory makes for a large /srv/mediawiki/.git
The flattening of the mediawiki directory has been running for a week on
beta. The size of /srv/mediawiki/.git yesterday was 829 MB, after a
git gc it was 334 MB.
This commit runs git gc --auto for every deployment on
/srv/mediawiki. It also handles clean up of tags for all scap3 repos,
since there are a lot hanging around.
Should fix T112509