Revert "Fixed ability to delete chat as forum with all topics."

This reverts commit f40064333e.

This destroys messages that were not really deleted.

Telegram/SourceFiles/history/history.cpp

@@ -4020,11 +4020,6 @@ void History::clear(ClearType type, bool markEmpty) {
 	} else if (const auto channel = peer->asMegagroup()) {
 		channel->mgInfo->markupSenders.clear();
 	}
-	if (const auto forum = peer->forum()) {
-		forum->enumerateTopics([&](not_null<Data::ForumTopic*> topic) {
-			destroyMessagesByTopic(topic->rootId());
-		});
-	}
 
 	owner().notifyHistoryChangeDelayed(this);
 	owner().sendHistoryChangeNotifications();