review-build-cng-env - Use a GIT_DEPTH of 1

Context

See EPIC and the related potential improvement on the jobs page.

Goal

Experiment with a GIT_DEPTH of 1 to reduce the time it takes to do a git clone, in particular if the job doesn't use the git history! (think git diff).

Why it matters: We use a GIT_FETCH of 20 by default, and it takes around 25 seconds for a git clone to happen for the GitLab project.

After this experiment

If this experiment is successful, please have a look at other jobs in the review apps pipeline, to see if there are other jobs that could benefit from the same change.

In particular, identify the jobs that rely on the git history, and that couldn't use that change.

Hint: Search on the jobs page for Same remarks as for for the job you are working on.

Documentation

Please document your findings on the jobs page.