Use 4 WSGI workers on 64bit systems
    
    Commit f1d5ab3a03191dbb02e5f95308cf8c4f1971cdcf increases WSGI worker
    count to five. This turned out to be a bit much for our test systems.
    Four workers are good enough and still double the old amount.
    
    See: https://pagure.io/freeipa/issue/7587
    Signed-off-by: Christian Heimes <cheimes@redhat.com>