qa/tasks/thrashosds-health: fine tune ignorelist for degraded and undersized pgs

qa/tasks/thrashosds-health: fine tune ignorelist for degraded and undersized pgs

These warnings, part of the Ceph health detail, are expected in osd thrashing
tests. In the original test failure, the cluster eventually got back to
HEALTH_OK after the thrashing task completed.

Fixes: https://tracker.ceph.com/issues/72312
Signed-off-by: Laura Flores <lflores@ibm.com>
Conflicts:
	qa/tasks/thrashosds-health.yaml - OSD_DOWN warnings were not present when the commit was first made