Use Kaniko to build containers in AutoDevOps

With the changes in %11.2, GitLab now supports Kaniko. We should swap out docker build for kaniko in Auto DevOps, so we reduce the need for a privileged runner.

Issues With Kaniko

There are some issues with using kaniko builds that need to be resolved before we can think about trying kaniko again:

• Slow filesystem snapshots https://gitlab.com/gitlab-org/gitlab-ce/issues/50313#note_157460108
• sudo permissions sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set error building image: error building (https://gitlab.com/gitlab-org/gitlab-ce/issues/60064)