Fixes #39046

Fixes gitaly#629

Replaces all the explicit include metadata syntax in the specs (tag:
true) into the implicit one (:tag).
Added a cop to prevent future errors and handle autocorrection.

This reverts commit 1d3c33b5.

When calling pre-receive, post-receive, and update hooks, add the GitLab
username as the GL_USERNAME environment variable.

This patch only handles cases where pushes are over http, or via
the web interface.  Later, we will address the ssh case.

If the ref doesn't exist, and the source branch is deleted, we can't get it back
easily. Previously, we ignored this error by shelling out, so replicate that
behaviour.

In gitlab-org/gitlab-ee!2976, we saw that a given OID could point
to a commit, which would cause the delta size check to fail.
Gitaly already returns nil if the OID isn't a blob, so this change
makes the Rugged implementation consistent.

This allows the current Gitaly migration to depend on less code outside
of the Gitlab::Git module

Users of project mirrors would see that the number of branches did not
match the number in the branch dropdown because remote branches were
counted when Rugged was in use. With Gitaly, only local branches
are counted.

Closes #36934

Add `:broken_storage` metadata to examples to disable this behavior only
when necessary.

This allows testing every storage attempt after a failure. Which could
be useful for tests

Signed-off-by: Rémy Coutable <remy@rymai.me>

Also fix a few tests