config.json: remove duplicate "EnableUserTypingMessages" (#5445)

config/config.json

@@ -41,7 +41,6 @@
         "PostEditTimeLimit": 300,
         "TimeBetweenUserTypingUpdatesMilliseconds": 5000,
         "EnableUserTypingMessages": true,
-        "EnableUserTypingMessages": true,
         "ClusterLogTimeoutMilliseconds": 2000
     },
     "TeamSettings": {