Do not allow new users to delete content by default

MediaBrowser.Model/Users/UserPolicy.cs

@@ -77,7 +77,7 @@ namespace MediaBrowser.Model.Users
 
         public UserPolicy()
         {
-            EnableContentDeletion = true;
+            EnableContentDeletion = false;
             EnableContentDeletionFromFolders = Array.Empty<string>();
 
             EnableSyncTranscoding = true;