openqa/worker: override kernel scheduler config
    
    This applies only within Fedora infra for now, as we're not sure
    whether worker hosts on different hardware hit this bug. It's
    intended to work around:
    https://bugzilla.redhat.com/show_bug.cgi?id=2009585
    a bug which results in the infra worker hosts hanging after a
    short time when running kernels newer than 5.11.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>