Do not remove wixpacks from items to sign (#60523)

They need to be in the list so that they are identified as the pack for an msi or exe that can be unpacked, signed, and then used to re-create the msi/exe.

Author: mmitche

eng/Signing.props

@@ -24,8 +24,6 @@
     <ItemsToSign Include="$(VisualStudioSetupOutputPath)**\*.vsix" />
     <ItemsToSign Include="$(ArtifactsDir)installers\$(Configuration)\**\*.exe" />
     <ItemsToSign Include="$(ArtifactsDir)installers\$(Configuration)\**\*.msi" />
-    <ItemsToSign Remove="$(ArtifactsDir)installers\$(Configuration)\**\*.wixpack.zip" />
-    <ItemsToSign Remove="$(ArtifactsPackagesDir)**\*.wixpack.zip" />
     <ItemsToSign Remove="$(ArtifactsPackagesDir)**\*symbols.nupkg" />
   </ItemGroup>