Merge branch 'no-downtime-check-stable' into 'master'

Don't run the downtime check on stable branches, or tags/master

See merge request !10794

.gitlab-ci.yml

@@ -201,7 +201,13 @@ rake config_lint: *exec
 rake brakeman: *exec
 rake flay: *exec
 license_finder: *exec
-rake downtime_check: *exec
+rake downtime_check:
+  <<: *exec
+  except:
+    - master
+    - tags
+    - /^[\d-]+-stable(-ee)?$/
+
 rake ee_compat_check:
   <<: *exec
   only: