Split Web UI test suite in nightly PR CI configuration (IPA 4.7)
    
    Manually apply changes from PRs:
    https://github.com/freeipa/freeipa/pull/2538
    https://github.com/freeipa/freeipa/pull/2774
    
    WebUI test suite configuration is split to 11 bunches of tests to avoid unexpected timeouts.
    test_webui/test_host.py runs standalone because it is unstable and heaviest one.
    
    Original task: https://pagure.io/freeipa/issue/7756
    
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>