gitlab-ci: equally delay all jobs on integration branches

When running a pipeline on an integration branch in `cmake/cmake`, delay
the lint jobs just as much as all the others.  This avoids starting them
unnecessarily during a sequence of merges over a short time range.

.gitlab/rules.yml

@@ -31,7 +31,8 @@
         - if: '$CI_MERGE_REQUEST_ID'
           when: on_success
         - if: '$CI_PROJECT_PATH == "cmake/cmake"'
-          when: on_success
+          when: delayed
+          start_in: 5 minutes
         - when: never
 
 .run_dependent: