chore(topology): remove commented out legacy code

Author: mbroadst

lib/core/sdam/topology.js

@@ -37,7 +37,6 @@ const clearAndRemoveTimerFrom = common.clearAndRemoveTimerFrom;
 const serverSelection = require('./server_selection');
 const readPreferenceServerSelector = serverSelection.readPreferenceServerSelector;
 const writableServerSelector = serverSelection.writableServerSelector;
-// const selectServers = serverSelection.selectServers;
 
 // Global state
 let globalTopologyCounter = 0;