Don't load events if not needed

(cherry picked from commit 7762f5f5ae)

src/messageeventmodel.cpp

@@ -90,7 +90,9 @@ void MessageEventModel::setRoom(NeoChatRoom *room)
     m_currentRoom = room;
     if (room) {
         room->setDisplayed();
-        room->getPreviousContent(50);
+        if (m_currentRoom->timelineSize() < 10) {
+            room->getPreviousContent(50);
+        }
         lastReadEventId = room->readMarkerEventId();
 
         using namespace Quotient;