test: Use virt-builder rhel-7.4 image as base
test: Use virt-builder rhel-7.4 image as base

Now that Red Hat Enterprise Linux 7.4 is available, we don't
need to test using composes.

petervo/cockpit,michalskrivanek/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,Scribery/cockpit,michalskrivanek/cockpit,petervo/cockpit,mareklibra/cockpit,larskarlitski/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,Scribery/cockpit,cockpituous/cockpit,SotolitoLabs/cockpit,cockpituous/cockpit,mvollmer/cockpit,cockpituous/cockpit,stefwalter/cockpit,moraleslazaro/cockpit,andreasn/cockpit,martinpitt/cockpit,deryni/cockpit,michalskrivanek/cockpit,andreasn/cockpit,stefwalter/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,garrett/cockpit,harishanand95/cockpit,xhad/cockpit,stefwalter/cockpit,garrett/cockpit,Scribery/cockpit,harishanand95/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,garrett/cockpit,moraleslazaro/cockpit,andreasn/cockpit,mareklibra/cockpit,petervo/cockpit,xhad/cockpit,SotolitoLabs/cockpit,stefwalter/cockpit,deryni/cockpit,cockpit-project/cockpit,harishanand95/cockpit,martinpitt/cockpit,larsu/cockpit,mvollmer/cockpit,petervo/cockpit,petervo/cockpit,Scribery/cockpit,cockpit-project/cockpit,larsu/cockpit,harishanand95/cockpit,cockpit-project/cockpit,larsu/cockpit,andreasn/cockpit,stefwalter/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,xhad/cockpit,SotolitoLabs/cockpit,michalskrivanek/cockpit,michalskrivanek/cockpit,moraleslazaro/cockpit,larsu/cockpit,stefwalter/cockpit,Scribery/cockpit,deryni/cockpit,deryni/cockpit,petervo/cockpit,xhad/cockpit,larskarlitski/cockpit,larskarlitski/cockpit,mareklibra/cockpit,mareklibra/cockpit,harishanand95/cockpit,SotolitoLabs/cockpit,mareklibra/cockpit,mvollmer/cockpit,michalskrivanek/cockpit,larskarlitski/cockpit,Scribery/cockpit,andreasn/cockpit,deryni/cockpit,larskarlitski/cockpit,garrett/cockpit,deryni/cockpit,xhad/cockpit,xhad/cockpit,petervo/cockpit,mvollmer/cockpit,andreasn/cockpit,martinpitt/cockpit,cockpituous/cockpit,garrett/cockpit,stefwalter/cockpit,deryni/cockpit,larskarlitski/cockpit,larskarlitski/cockpit,martinpitt/cockpit,larsu/cockpit,cockpituous/cockpit,xhad/cockpit,larsu/cockpit,harishanand95/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,martinpitt/cockpit,harishanand95/cockpit,michalskrivanek/cockpit,Scribery/cockpit