Dockerfile.gerrit: Upgrade to Gerrit 3.7.6 and use LFS plugin
We're currently using 3.7.6 in production.
Install the lfs plugin too. A future commit will establish
configuration for it.
Related MRs:
- !59 (merged) (This MR)
- !58 (merged)
- main
Depends-On: !58 (merged)
Edited by Ahmon Dancy