add rd_lobby_query_servers convar to completely disable ISteamMatchmakingServers usage.

Author: BenLubar

src/game/shared/swarm/rd_lobby_utils.cpp

@@ -349,6 +349,7 @@ static void DebugSpewLobby( CSteamID lobby )
 #define LOBBY_SEARCH_INTERVAL 30.0f
 
 ConVar rd_lobby_search_debug( "rd_lobby_search_debug", "0" );
+ConVar rd_lobby_query_servers( "rd_lobby_query_servers", "0" );
 
 CReactiveDropLobbySearch::CReactiveDropLobbySearch( const char *pszDebugName ) :
 	m_DistanceFilter{ k_ELobbyDistanceFilterWorldwide },
@@ -605,6 +606,9 @@ CReactiveDropServerListHelper::~CReactiveDropServerListHelper()
 
 void CReactiveDropServerListHelper::WantUpdatedServerList()
 {
+	if ( !rd_lobby_query_servers.GetBool() )
+		return;
+
 	if ( m_hServerListRequestNext || m_flSoonestServerListRequest > Plat_FloatTime() )
 		return;