Tests: Avoid skipping tests due to missing files
    
    When running test_install/test_updates and test_pkcs10/test_pkcs10 as
    outoftree, these are skipped with reason 'Unable to find test update files'.
    For outoftree tests wrong paths are checked for these files.
    Changing file localization to provide proper test setup.
    
    https://fedorahosted.org/freeipa/ticket/6284
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>