Remove "docker" in backend artifacts

Reference (only slides 6, 7, 8 and 10 are applicable to this task): https://docs.google.com/presentation/d/1izVpDcaIP9WDnFBBG-Oc2ccaBqsVe8qPOGroaDA8dj0/edit?usp=sharing

1. Migrate container repositories from http://pkgs.devel.redhat.com/cgit/rpms to http://pkgs.devel.redhat.com/cgit/containers, while dropping the "-docker" suffix from the repo name

2. In Brew, replace "-docker" with "-container" in package name and "-docker-candidate" with "-containers-candidate" in target name

3. In Errata tool, make sure package name is update with new name from step 2

4. In Dockerfile, replace "-docker" with "-container" in LABEL com.redhat.component; also change ENV container=docker to ENV container=oci; finally also change other occurrences like description

For consulting please contact sgajanur@redhat.com.