Fix AHelp progressively showing more AHelp panels (#20591)

Content.Client/Administration/UI/Bwoink/BwoinkControl.xaml.cs

@@ -235,6 +235,7 @@ namespace Content.Client.Administration.UI.Bwoink
 
             if (ch != null)
             {
+                AHelpHelper.HideAllPanels();
                 var panel = AHelpHelper.EnsurePanel(ch.Value);
                 panel.Visible = true;
             }

Content.Client/UserInterface/Systems/Bwoink/AHelpUIController.cs

@@ -437,6 +437,14 @@ public sealed class AdminAHelpUIHandler : IAHelpUIHandler
         }
     }
 
+    public void HideAllPanels()
+    {
+        foreach (var panel in _activePanelMap.Values)
+        {
+            panel.Visible = false;
+        }
+    }
+
     public BwoinkPanel EnsurePanel(NetUserId channelId)
     {
         EnsureControl();