CmdPal: Hide selection indicator (pill) from items in the context menu (#44563)

## Summary of the Pull Request

This PR removes the selection indicator from the list view used for the
context menu to maintain consistency with Fluent UI design guidelines.

## Pictures? Pictures!

Before:
<img width="338" height="287" alt="image"
src="https://github.com/user-attachments/assets/6b7cba0f-b127-4a6e-a7ee-985865f446c6"
/>


After:
<img width="366" height="372" alt="image"
src="https://github.com/user-attachments/assets/a91b9a88-19e7-47c0-a777-8722757cd874"
/>


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## PR Checklist

- [x] Closes: #44611
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issues) -->
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ContextMenu.xaml

@@ -134,6 +134,9 @@
             ItemsSource="{x:Bind ViewModel.FilteredItems, Mode=OneWay}"
             PreviewKeyDown="CommandsDropdown_PreviewKeyDown"
             SelectionMode="Single">
+            <ListView.Resources>
+                <x:Boolean x:Key="ListViewItemSelectionIndicatorVisualEnabled">False</x:Boolean>
+            </ListView.Resources>
             <ListView.ItemContainerStyle>
                 <Style BasedOn="{StaticResource DefaultListViewItemStyle}" TargetType="ListViewItem">
                     <Setter Property="MinHeight" Value="0" />