1. Modify the repeat time from 300 to 100 about with_repetition test.
   Repeat 300 times takes too long time.
2. Modify the repeat time from 3 to 1 about not repetition test.
   Repeat hotplug and unplug can be covered by with_repetition test.
3. Limited the with_shutdown.after_plug only with_plug,
   When test without_plug, this case is no needed.
Signed-off-by: NPeixiu Hou <phou@redhat.com>