1. add s390x support to docker images `executor`, `executor(slim)`,
`executor(debug)` and `warmer`. Fixes#1462 and #1665.
2. Address the building issue of dependency `docker-credential-gcr`
in Dockerfiles. This issue was introduced when recent commits
in `docker-credential-gcr` removed the Makefile.
Signed-off-by: Kun-Lu <kun.lu@ibm.com>
Co-authored-by: Kun-Lu <kun.lu@ibm.com>