Enable image executor opts in the kubernetes executor

Cannot specify "root" user to run a job [Kubern... (#38942 - closed) reports that they cannot set the user image executor opts in the executorkubernetes. But, but, we added support for than in Specify which "user" shall run the job from the... (!5469 - merged). But, but, we did not enable it by reporting to gitlab that the executor supports that feature ☹️.

Note that the first commit just sorts the features alphabetically for easier comparison, so can be skipped.

Fixes Cannot specify "root" user to run a job [Kubern... (#38942 - closed)