Remove unnecessary properties from SystemInfo response object

These properties do not provide any useful information to the client. The client would already have to have all this information in order to connect to the endpoint to retrieve it

MediaBrowser.Model/Configuration/ServerConfiguration.cs

@@ -234,11 +234,6 @@ namespace MediaBrowser.Model.Configuration
         /// </summary>
         public bool RequireHttps { get; set; }
 
-        /// <summary>
-        /// Gets or sets a value indicating whether the server is behind a reverse proxy.
-        /// </summary>
-        public bool IsBehindProxy { get; set; }
-
         public bool EnableNewOmdbSupport { get; set; }
 
         public string[] RemoteIPFilter { get; set; }