use compose repository (not master repo) for most tests
    
    Summary:
    we have a long-standing problem with all the tests that hit
    the repositories. The tests are triggered as soon as a compose
    completes. At this point in time, the compose is not synced to
    the mirrors, where the default 'fedora' repo definition looks;
    the sync happens after the compose completes, and there is also
    a metadata sync step that must happen after *that* before any
    operation that uses the 'fedora' repository definition will
    actually use the packages from the new compose. Thus all net
    install tests and tests that installed packages have been
    effectively testing the previous compose, not the current one.
    
    We have some thoughts about how to fix this 'properly' (such
    that the openQA tests wouldn't have to do anything special,
    but their 'fedora' repository would somehow reflect the compose
    under test), but none of them is in place right now or likely
    to happen in the short term, so in the mean time this should
    deal with most of the issues. With this change, everything but
    the default_install tests for the netinst images should use
    the compose-under-test's Everything tree instead of the 'fedora'
    repository, and thus should install and test the correct
    packages.
    
    This relies on a corresponding change to openqa_fedora_tools
    to set the LOCATION openQA setting (which is simply the base
    location of the compose under test).
    
    Test Plan:
    Do a full test run, check (as far as you can) tests run sensibly
    and use appropriate repositories.
    
    Reviewers: jskladan, garretraziel
    
    Reviewed By: garretraziel
    
    Subscribers: tflink
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D989