varnish: git.wm.org to antimony, remove git-related config/tests
This would be in case we decide that we don't want to put the rewrite
rules on the cluster anyways and put them on iridium instead.
If we do that then the backend needs to be changed here and my DNS
change to point it to text cluster can be abandoned (I8a7d3245e320160),
and Ide401ee9526995bcc23e8 shoud be amended so that the rules end up
on iridium instead of the cluster.
This is also removing config that was specifically for gitblit and
should not be needed anymore.
I am not 100% sure if those tests should be deleted like that though.