Dismiss the details pane when the list gets emptied (#39206)

I cannot find an issue for this. I swear I filed it somewhere.

If you open winget, search for "terminal", wait till it loads, then
hit `esc`, we'll clear the search and empty the list, but never actually
hide the details pane. That looks weird.

This fixes that.

Closes _nothing i guess_.

src/modules/cmdpal/Microsoft.CmdPal.UI/Pages/ShellPage.xaml.cs

@@ -418,9 +418,6 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
     {
         _ = DispatcherQueue.TryEnqueue(() =>
         {
-            // Also hide our details pane about here, if we had one
-            HideDetails();
-
             if (_settingsWindow == null)
             {
                 _settingsWindow = new SettingsWindow();