Ship git 2.16
Geo needs git 2.16 for performance reasons. To make git 2.16 work, we are working on an automatic cleanup before push via a number of merge requests:
I believe gitaly!622 (merged) was already shipped with 10.6, so we have already pruned some but not all stale worktrees.
Once these are merged, I propose that we ship git 2.16 with omnibus-gitlab again.