Cleanup - Use RemoveAllChildren() over DisposeAllChildren() (#39848)

* Content - change the (should-be-obsolete) DisposeAllChildren into the more robust RemoveAllChildren.

* Remove duplicate calls.

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Co-authored-by: ElectroJr <leonsfriedrich@gmail.com>

Content.Client/Access/UI/AgentIDCardWindow.xaml.cs

@@ -41,7 +41,7 @@ namespace Content.Client.Access.UI
 
         public void SetAllowedIcons(string currentJobIconId)
         {
-            IconGrid.DisposeAllChildren();
+            IconGrid.RemoveAllChildren();
 
             var jobIconButtonGroup = new ButtonGroup();
             var i = 0;