gitlab CI: update to use the latest CI templates

Repository was moved there from wayland/ci-templates, and let's update to the
most recent version..

No real functional changes, we're just making use of the various CI template
bits and bobs now, specifically the FDO_* variables and the
.fdo.container-build and .fdo.distribution-image templates.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>