Make CKI approvals required

Changes to CKI are critical for the workflow functionality and thus really should be reviewed. Otherwise, changes to the CI definitions can get accidentally merged if the author either thinks their solution is correct, if they changed the CI definition for testing and forgot to switch it back, submitted the MR from the incorrect branch and changed the whole file and didn't notice... Such changes can very easily break the CI for the whole repo/branch and are easy to miss if there's no required approval for them.

Any actual CI changes that should be merged because of kernel changes are pretty rare (e.g. disttag and container changes during branching) and any changes due to internal CKI functionality are done by the CKI team, so the impact on the developers should be minimal in any case.

Signed-off-by: Veronika Kabatova vkabatov@redhat.com