media_server: Fix fetching the team_id from the SOME_APP_QUIT message.

Now the buffers of crashed teams will actually be removed from the
media_server. (Was this code just never tested?!)

src/servers/media/media_server.cpp

@@ -952,7 +952,7 @@ ServerApp::MessageReceived(BMessage* msg)
 				gNodeManager->CleanupDormantFlavorInfos();
 
 			team_id id;
-			if (msg->FindInt32("team", &id) == B_OK
+			if (msg->FindInt32("be:team", &id) == B_OK
 					&& gAppManager->HasTeam(id)) {
 				gAppManager->UnregisterTeam(id);
 			}