lisa: Use git protocol instead of HTTP when cloning gitlab

Gitlab seems to have some troubles with HTTPS clones redirecting to sign
in page, so use git protocol instead.

.github/workflows/gitlab-mirror.yml

@@ -31,7 +31,7 @@ jobs:
           set -x
 
           cd target-repo || exit 1
-          git remote add gitlab https://git.gitlab.arm.com/tooling/lisa.git
+          git remote add gitlab git@git.gitlab.arm.com:tooling/lisa.git
 
           function mirror() {
               local ref=$1