ipatests: test if KRA install fails when ca_host is overriden
    
    KRA install on a replica should fail if ca_host is
    overriden in /etc/ipa/default.conf.
    
    Related: https://pagure.io/freeipa/issue/8245
    Signed-off-by: Antonio Torres <antorres@redhat.com>
    Reviewed-By: François Cami <fcami@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>