mgr/progress/module.py: s/events/_events/ #29625

mgr/progress/module.py: s/events/_events/ #29625

Fixes time out failure because the module was trying to accessing
attribute events line 437 in this block of code:

435 if marked == "in":
436 for ev_id in list(self._events):
437 ev = self.events[ev_id]
438 if isinstance(ev, PgRecoveryEvent) and osd_id in ev.which_osds:
439 self.log.info("osd.{0} came back in, cancelling event".format(
440 osd_id
441 ))
442 self._complete(ev)

Therefore, it wouldn't trigger an event

Fixes: https://tracker.ceph.com/issues/40618
Signed-off-by: Kamoltat (Junior) Sirivadhna <ksirivad@redhat.com>