Currently, the buildah clustertask accepts a `dockerconfig` workspace which expects `config.json` at the root, while it's common practice that users create `dockerconfigjson` secrets with the key `.dockerconfigjson` and not `config.json`

We should accept secrets with either key `config.json` or `.dockerconfigjson` with priority to `config.json`

This needs to be fixed in `source_local` in the operator as well as in upstream catalog

For more see:

• https://gitlab.cee.redhat.com/tekton/p12n/-/merge_requests/235#note_4769645
• https://coreos.slack.com/archives/CG5GV6CJD/p1661952656114739