Fix netmask in nova_fixed for non-production
Fix netmask in nova_fixed for non-production

Production clouds start with `p` and have a larger subnet at their
disposal. The current test for production cloud is overly broad and
captures clouds such as `vp5` which have smaller networks.

vmoravec/automation,aspiers/automation,aspiers/automation,gosipyan/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,aspiers/automation,vmoravec/automation,SUSE-Cloud/automation,gosipyan/automation,aspiers/automation,gosipyan/automation,vmoravec/automation,SUSE-Cloud/automation,gosipyan/automation,vmoravec/automation