Test for 7526
    
    Add a test for issue 7526: install a client with a bulk enrollment
    password, enrolling to an externally-signed CA master.
    Without the fix, the master does not publish the whole cert chain
    in /usr/share/ipa/html/ca.crt. As the client installer downloads the
    cert from this location, client installation fails.
    With the fix, the whole cert chain is available and client installation
    succeeds.
    The test_external_ca.py::TestExternalCA now requires 1 replica and 1
    client, updated .freeipa-pr-ci.yaml accordingly.
    
    Also removed the annotation @tasks.collect_logs from test_external_ca
    as it messes with test ordering (and the test collects logs even
    without this annotation).
    
    Related to:
    https://pagure.io/freeipa/issue/7526
    
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>