Remove the NuGetPackageInstaller wizard from the C# templates

[lauren-ciha]

The NuGetPackageInstaller wizard was created to unify the package installation process for the C# and C++ Windows App SDK templates. With the addition of C# dotnet templates in #6407, it made sense to instead unify the package installation process between the C# templates with the built-in PackageReference behavior #6523. Now that both the .NET and VS templates use PackageReference, the NuGetPackageInstaller wizard is no longer needed for the C# templates. This PR removes that wizard, eliminating the main difference between the .NET and VS templates.

Validation (manual):

• Tested locally via (script)
• Ran the pipeline to generate the Standalone VSIX
• For each of the C# templates, I verified that the Standalone VSIX installed successfully and the NuGetPackageInstaller wizard was no longer present when creating C# template projects

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[DinahK-2SO]

Hi @lauren-ciha , I approved this PR.

I found the template pipeline failed, but it's failed on the dotnet new smoke tests, doesn't seem related to this PR updating for the VSIX packages.

If the template pipeline blocks your merge please let me know.

[lauren-ciha]

/azp run

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