[Run] Remove unused namespaces (#46221)

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## Summary of the Pull Request

Related: #46220

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## PR Checklist

- [ ] Closes: #xxx
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- [ ] **Communication:** I've discussed this with core contributors
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- [ ] **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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## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed

src/modules/launcher/PowerLauncher/App.xaml

@@ -2,7 +2,6 @@
     x:Class="PowerLauncher.App"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
     ShutdownMode="OnMainWindowClose"
     Startup="OnStartup">
     <Application.Resources>

src/modules/launcher/PowerLauncher/ResultList.xaml

@@ -7,7 +7,6 @@
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:p="clr-namespace:PowerLauncher.Properties"
-    xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
     xmlns:viewModel="clr-namespace:PowerLauncher.ViewModel"
     d:DesignHeight="300"
     d:DesignWidth="720"