gitlab-ci: do some basic testing on ubuntu1804-32bit

gitlab-ci: do some basic testing on ubuntu1804-32bit

For now we allow build warnings and only do some basic testing.
We also ignore timestamp related problems, as well as some charset
failures.

Over time we should try to address the situation by not allowing warnings
and verify if expected failures are harmless or not.

But it's already much better then having no 32bit testing at all!

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Thu Nov 24 12:05:26 UTC 2022 on sn-devel-184