gitlab: switch from 'stable' to 'latest' docker container tags

gitlab: switch from 'stable' to 'latest' docker container tags

The 'stable' and 'stable-dind' tags are not documented as supported
tags at:

  https://hub.docker.com/_/docker

Looking at their content they reflect docker 19.x.x release series,
were last built in Dec 2020, and have 3 critical and 20 high rated
CVEs unfixed. This obsolete status is attested by this commit:

  https://github.com/docker-library/docker/commit/606c63960a4845af7077721eb3900c706f5d0c5e

The 'stable-dind' tag in particular appears buggy as it is unable to
resolve DNS for Fedora repos:

  - Curl error (6): Couldn't resolve host name for https://mirrors.fedoraproject.org/metalink?repo=fedora-37&arch=x86_64&countme=1 [getaddrinfo() thread failed to start]

We used the 'stable' tag previously at the recommendation of GitLab
docs, but those docs are wrong and pending a fix:

  https://gitlab.com/gitlab-org/gitlab/-/issues/409430

Fixes: 5f63a67adb58478974b91f5e5c2b1222b5c7f2cc
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Camilla Conte <cconte@redhat.com>
Message-Id: <20230531140654.1141145-1-berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>