Always validate Custom Script path

(cherry picked from commit c922cc5dc617dd776d4523cbf62376821c5a4ad9)

src/NzbDrone.Core/Notifications/CustomScript/CustomScript.cs

@@ -285,14 +285,6 @@ namespace NzbDrone.Core.Notifications.CustomScript
                 failures.Add(new NzbDroneValidationFailure("Path", "File does not exist"));
             }
 
-            foreach (var systemFolder in SystemFolders.GetSystemFolders())
-            {
-                if (systemFolder.IsParentPath(Settings.Path))
-                {
-                    failures.Add(new NzbDroneValidationFailure("Path", $"Must not be a descendant of '{systemFolder}'"));
-                }
-            }
-
             if (failures.Empty())
             {
                 try

src/NzbDrone.Core/Notifications/CustomScript/CustomScriptSettings.cs

@@ -11,6 +11,7 @@ namespace NzbDrone.Core.Notifications.CustomScript
         public CustomScriptSettingsValidator()
         {
             RuleFor(c => c.Path).IsValidPath();
+            RuleFor(c => c.Path).SetValidator(new SystemFolderValidator()).WithMessage("Must not be a descendant of '{systemFolder}'");
             RuleFor(c => c.Arguments).Empty().WithMessage("Arguments are no longer supported for custom scripts");
         }
     }