ipatests: healthcheck: Handle missing fips-mode-setup
    
    freeipa-healthcheck prechecks existance of `fips-mode-setup` and
    reports if it's missing:
    > "fips": "missing /bin/fips-mode-setup"
    
    Fixes: https://pagure.io/freeipa/issue/9315
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>