ipatests: run test_ipahealthcheck.py::TestIpaHealthCheck separately
    
    The test is changing the date back and forth. Due to PRCI
    infra issue, chronyd is not able to connect to the default
    NTP servers from the fedora pool, and the date is not
    synchronized any more after this test.
    
    To avoid polluting other tests, run this one separately.
    
    Fixes: https://pagure.io/freeipa/issue/8472
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>