Remove ngen uninstall workarounds

Within the SDK images there are several ngen uninstall calls to remove assemblies that have been queued to be ngen'd but fail to ngen. In order to remove the workarounds, VS will need to address their issues first.

Example:

RUN `
    # Workaround for issue with 32 bit assemblies from .NET Framework 4.8 SDK being 64 bit ngen'ed
    \Windows\Microsoft.NET\Framework64\v4.0.30319\ngen uninstall "C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools\SecAnnotate.exe" `
    && \Windows\Microsoft.NET\Framework64\v4.0.30319\ngen uninstall "C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools\WinMDExp.exe" `
    `
    && \Windows\Microsoft.NET\Framework64\v4.0.30319\ngen update `
    `
    # Workaround VS installer/ngen issues
    && \Windows\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "C:\Program Files (x86)\Microsoft Visual Studio\2019\TestAgent\Common7\IDE\VSWebLauncher.exe" `
    && \Windows\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "C:\Program Files (x86)\Microsoft Visual Studio\2019\TestAgent\Common7\IDE\CommonExtensions\Microsoft\Editor\Microsoft.VisualStudio.Diff.CommandLineSwitch.pkgdef" `
    && \Windows\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "C:\Program Files (x86)\Microsoft Visual Studio\2019\TestAgent\Common7\IDE\CommonExtensions\Microsoft\Editor\Microsoft.VisualStudio.Diff.pkgdef" `
    `
    && \Windows\Microsoft.NET\Framework\v4.0.30319\ngen update

Start by locating the SDK image definitions containing the shown ngen uninstall commands and review the Visual Studio installer and ngen issues referenced in the issue. Done means those issues are addressed, the workaround commands are removed, and the affected images still build successfully.