fix(config) drop useStunTurn

Always attempt to discover the configured STUN/TURN servers.

config.js

     // is set in Jicofo and set to 2).
     // minParticipants: 2,
 
-    // Use the TURN servers discovered via XEP-0215 for the jitsi-videobridge
-    // connection
-    // useStunTurn: true,
-
     // Use TURN/UDP servers for the jitsi-videobridge connection (by default
     // we filter out TURN/UDP because it is usually not needed since the
     // bridge itself is reachable via UDP)
         // connection.
         enabled: true,
 
-        // Use XEP-0215 to fetch STUN and TURN servers.
-        // useStunTurn: true,
-
         // The STUN servers that will be used in the peer to peer connections
         stunServers: [
 

debian/jitsi-meet-turnserver.postinst

             echo "------------------------------------------------"
         fi
 
-        # Enable turn server in config.js
-        if [ -f $JITSI_MEET_CONFIG ] ; then
-            sed -i "s/\/\/ useStunTurn: true/useStunTurn: true/g" $JITSI_MEET_CONFIG
-        fi
-
         # and we're done with debconf
         db_stop
     ;;

react/features/base/config/configWhitelist.js

 /**
  * The config keys to whitelist, the keys that can be overridden.
  * Currently we can only whitelist the first part of the properties, like
- * 'p2p.useStunTurn' and 'p2p.enabled' we whitelist all p2p options.
+ * 'p2p.enabled' we whitelist all p2p options.
  * The whitelist is used only for config.js.
  *
  * @type Array
     'stereo',
     'subject',
     'testing',
-    'useStunTurn',
     'useTurnUdp',
     'videoQuality.persist',
     'webrtcIceTcpDisable',