ci: Use job templates via 'extends'
ci: Use job templates via 'extends'

This is the native way to implement templated jobs in GitLab CI,
as opposed to plain text replacement YAML level.

The names of the templates are updated to more closely match
those used in libvirt's gitlab-ci.yml.

Signed-off-by: Andrea Bolognani <3ada0bee826c753786fdbba72243dfba997094cf@redhat.com>

libvirt/libvirt-glib,libvirt/libvirt-glib,libvirt/libvirt-glib