Revert "attempt to accommodate late joiners for ds on flash"

.../src/main/scala/org/bigbluebutton/core/MeetingActor.scala

.../src/main/scala/org/bigbluebutton/core/MeetingModel.scala

...c/main/scala/org/bigbluebutton/core/api/OutMessages.scala

...src/main/scala/org/bigbluebutton/core/apps/UsersApp.scala

...on/core/pubsub/senders/DeskShareEventRedisPublisher.scala

...core/pubsub/senders/DeskShareMessageToJsonConverter.scala

...messages/DeskShareNotifySingleViewerRTMPEventMessage.java

...org/bigbluebutton/red5/client/DeskShareMessageSender.java