Fetch deeper the tested branch before fetching master

The tested branch is clone with a deep of 20 so if it has more than 20
commits, we need to deepen its hitory to be able to find the merge-base
with origin/master.

Also, detect prefixed EE branch as well, i.e. `ee-<branch>`.
Signed-off-by: Rémy Coutable <remy@rymai.me>

.gitlab-ci.yml

@@ -206,10 +206,9 @@ rake ee_compat_check:
     - /^[\d-]+-stable(-ee)?$/
   allow_failure: yes
   cache:
-    key: "ruby233-ee_compat_check_repo"
+    key: "ee_compat_check_repo"
     paths:
-      - ee_compat_check/repo/
-      - vendor/ruby
+      - ee_compat_check/ee-repo/
   artifacts:
     name: "${CI_JOB_NAME}_${CI_COMIT_REF_NAME}_${CI_COMMIT_SHA}"
     when: on_failure