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

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

* Remove duplicate calls.

---------

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

Content.Client/UserInterface/Systems/Ghost/Controls/GhostTargetWindow.xaml.cs

@@ -45,7 +45,7 @@ namespace Content.Client.UserInterface.Systems.Ghost.Controls
 
         public void Populate()
         {
-            ButtonContainer.DisposeAllChildren();
+            ButtonContainer.RemoveAllChildren();
             AddButtons();
         }
 

Content.Client/UserInterface/Systems/Ghost/Controls/Roles/GhostRolesWindow.xaml.cs

@@ -26,7 +26,7 @@ namespace Content.Client.UserInterface.Systems.Ghost.Controls.Roles
         public void ClearEntries()
         {
             NoRolesMessage.Visible = true;
-            EntryContainer.DisposeAllChildren();
+            EntryContainer.RemoveAllChildren();
             _collapsibleBoxes.Clear();
         }
 

Content.Client/UserInterface/Systems/Hands/Controls/HandsContainer.cs

@@ -1,4 +1,4 @@
-using System.Linq;
+using System.Linq;
 using Content.Client.UserInterface.Systems.Inventory.Controls;
 using Robust.Client.UserInterface.Controls;
 
@@ -74,7 +74,7 @@ public sealed class HandsContainer : ItemSlotUIContainer<HandButton>
     public void Clear()
     {
         ClearButtons();
-        _grid.DisposeAllChildren();
+        _grid.RemoveAllChildren();
     }
 
     public IEnumerable<HandButton> GetButtons()