Ensure the archiver deletes events from redis for the last segment

Issue #6338

It looks like there was a logic error in the code that was causing it
to break out of the event deletion loop early when deleting events for
the last (or only) segment in a recording. (In this case, last_index
is -1, so i >= last_index is always true).

The trim_events_for call was always succeeding, so the events were
being removed from the event list (meeting:{ID}:recordings key) even
though the events themselves hadn't been deleted in the loop.

I've moved the trim_events_for call to below the event deletion loop
to ensure that if the archive script is interrupted, the events list
will contain all not-yet-deleted events.

record-and-playback/core/lib/recordandplayback/events_archiver.rb

@@ -342,11 +342,11 @@ module BigBlueButton
 
       # Once the events file has been written, we can delete this segment's
       # events from redis.
-      @redis.trim_events_for(meeting_id, last_index)
       msgs.each_with_index do |msg, i|
         @redis.delete_event_info_for(meeting_id, msg)
-        break if i >= 0 and i >= last_index
+        break if last_index >= 0 and i >= last_index
       end
+      @redis.trim_events_for(meeting_id, last_index)
 
     end