Force the use of the rhel kernel cache for kwf pipelines

Normally, the filename of the git cache tarball is derived from the owner (last directory component of the repo URL) and the repository name. For the kernel workflow pipelines in the internal pipeline repo, the triggering repositories are normally located at something like https://gitlab.com/..../kernel/rhel-X, which results in an owner of 'kernel'. If the last directory component (ie owning GitLab group) is different, the git cache tarball cannot be found.

To make those repositories work as well, ensure the owner of the git cache is always set to kernel.