fix(noir-mirror): don't update .gitrepo on push (AztecProtocol#4555)

We no longer need a commit on aztec side, and if we forgo this we're a
bit more robust actually because then the base URL is always the last
pull
There is a heuristic for finding the last commit that should be
considered 'synced' for commit message computation purposes. The
heuristic failed because
1. there were extra commits in aztec packages after our pull
2. then when we fell back to our gitrepo commit, it was changed on sync

To fix this, we can exploit not needing to actually know our last pushed
commit as we know squash. This way, our 'commit' variable in our
.gitrepo is always our last *pull* and not pull or push

.github/workflows/mirror_noir_subrepo.yml

@@ -95,9 +95,8 @@ jobs:
             COMMIT=$(git rev-parse HEAD)
             # Now push to it with subrepo with computed commit messages
             if ./scripts/git-subrepo/lib/git-subrepo push $SUBREPO_PATH --squash --branch=$STAGING_BRANCH; then
+              # We don't push a commit to aztec anymore so that we can maintain the 'commit' as our last pull branch
               git reset $COMMIT
-              git commit --allow-empty --amend -am "$(git log -1 --pretty=%B) [skip ci]"
-              git push
             else
               echo "Problems syncing noir. We may need to pull the subrepo."
               exit 1
@@ -109,7 +108,7 @@ jobs:
             cd noir-repo
             git fetch # see recent change
             git checkout $BRANCH || git checkout -b $BRANCH
-            git merge -Xtheirs $STAGING_BRANCH
+            git merge -Xtheirs origin/$STAGING_BRANCH
             git push origin $BRANCH
             cd ..
           }

noir/.gitrepo

@@ -6,7 +6,7 @@
 [subrepo]
 	remote = https://github.com/noir-lang/noir
 	branch = aztec-packages
-	commit = 5f5843e35052b9d3599b8ab4f7633db0a225e82f
-	parent = e5ca533ea4513cf3c6b7e3eb057083838b861a6b
+	commit = 6ff518af281afe601edb8574d425b07d9d2f9c5d
+	parent = 2082fedfb03d4882a269881f51c5337263bc539b
 	method = merge
 	cmdver = 0.4.6