always use --nogpgcheck when installing packages
    
    Summary:
    Except when running on the pre-upgrade release in the upgrade
    tests (where GPG check should always be OK).
    
    Currently we always need to use --nogpgcheck on Rawhide, and we
    must also use it on Branched prior to the Bodhi activation
    point. At present we don't really have any simple way to know
    when the Bodhi activation point has kicked in. We could assume
    that it's safe to do GPG checking for 'candidate' (not nightly)
    composes, but even that isn't 100% safe and isn't really the
    *right* thing to do. So I think for now it's best to just always
    use --nogpgcheck , until we come up with a decent way to check
    for Bodhi enablement, or releng figures things out so we can
    rely on packages being signed in Rawhide and in Branched before
    Bodhi enablement.
    
    Test Plan:
    Check the tests all still run, make sure I didn't
    miss any dnf calls.
    
    Reviewers: jskladan, garretraziel
    
    Reviewed By: garretraziel
    
    Subscribers: tflink
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D964