tests: replace standard-test-rpm with -basic
    
    Currently, tests fail with
    
        TASK [standard-test-rpm : Install the test subject RPMs] ***********************
        fatal: [/workDir/workspace/fedora-rawhide-pr-pipeline/images/test_subject.qcow2]: FAILED! =>
          msg: '''subjects'' is undefined'
    
    'subjects' should be a list of RPMs to install but it looks undefined
    in fedora-rawhide-pr-pipeline.
    
    Try replacing this with standard-test-basic as seen in Fedora CI docs:
    
    https://docs.fedoraproject.org/en-US/ci/how-to-add-dist-git-test/
    
    Same doc describes standard-test-rpm as "A role for installing
    additional rpms" which I don't think is the use case here.