gitlab-ci: use CI templates from production branch

The kernel_templates.yml file is pulled directly from
pipeline-definition in the parent pipeline. While CKI can test new
versions of the child pipelines via the cki-bot instrumentation, that is
not possible for anything related to the parent pipeline.

To at least make it possible to test-run changes before merging an MR in
pipeline-definition, pull the kernel_templates.yml file from the
production branch. This branch can be updated via a manual job from
pipeline-definition MRs and easily rolled back without going through a
full git revert cycle.

Bugzilla: INTERNAL
Upstream Status: RHEL-only

Signed-off-by: Michael Hofmann <mhofmann@redhat.com>

Author: mh21

.gitlab-ci.yml

@@ -6,7 +6,7 @@
 
 include:
   - project: cki-project/pipeline-definition
-    ref: main
+    ref: production
     file: kernel_templates.yml
 
 workflow: !reference [.workflow]