CI: add ark-latest baseline job to tag cki-gating for successful pipelines

For ark-latest branch HEAD pipelines, add an on_success job after all the child pipelines that will update the cki-gating branch.

Before CKI builder-rawhide/eln container images are deployed into production, smoke test kernel build pipelines will be triggered in this branch. Currently, these pipelines are configured for the kernel variant on Rawhide and ELN limited to the x86_64 architecture.

Part of containers#46 (closed)

Fixes #136 (closed)

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