ci: Break off the integration_tests template into more templates

ci: Break off the integration_tests template into more templates

There's quite a lot happening in the .integration_tests template
already even without adding upstream QEMU build into the mix.
Let's break the template into more pieces which can then reference
in the .integration_tests template when putting all the pieces back
together using YAML anchors.

Signed-off-by: Erik Skultety <eskultet@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>