Fix WIX7009 error using StandardDirectory in Windows Service installer documentation

[Copilot]

The WiX Toolset configuration in the Windows Service installer documentation was causing a WIX7009 error when users tried to build the installer project. The error occurred because WiX Toolset v4 introduced virtual symbols that conflict with the traditional TARGETDIR symbol.

Error details:

WIX7009	The Directory symbol 'TARGETDIR' conflicts with a virtual symbol. Use the 'override' access modifier to override the virtual symbol or use a different Id to avoid the conflict. Referenced from wixstd.wixlib

Solution:
Replaced the legacy TARGETDIR Directory structure with WiX v4's modern StandardDirectory approach:

<!-- Before -->
<Directory Id="TARGETDIR" Name="SourceDir">
    <Directory Id="ProgramFiles64Folder">
        <!-- nested directories -->
    </Directory>
</Directory>

<!-- After -->
<StandardDirectory Id="ProgramFiles64Folder">
    <!-- nested directories -->
</StandardDirectory>

This approach:

• Uses WiX v4's built-in StandardDirectory elements instead of legacy Directory nesting
• Avoids the virtual symbol conflict entirely (no need for override attributes)
• Follows WiX Toolset v4 best practices and is more future-proof
• Simplifies the directory structure while maintaining all functionality

Fixes #42363.

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Internal previews

📄 File	🔗 Preview link
docs/core/extensions/windows-service-with-installer.md	docs/core/extensions/windows-service-with-installer

[gewarren]

@IEvangelist The fix that Copilot suggests is different to the fix in the issue that uses a different ID to avoid conflict. Do you have a preference?

[Copilot]

@IEvangelist The fix that Copilot suggests is different to the fix in the issue that uses a different ID to avoid conflict. Do you have a preference?

I can implement either approach:

Current fix (commit b3f995e): Adds override="true" to TARGETDIR - follows the error message recommendation exactly.

Issue suggestion: Replace TARGETDIR/Directory structure with <StandardDirectory Id="ProgramFiles64Folder"> - uses WiX v4's modern approach and avoids the virtual symbol entirely.

Both fix the WIX7009 error. The StandardDirectory approach is more modern and future-proof. Which would you prefer @IEvangelist?

[gewarren]

@copilot please use the StandardDirectory solution instead.

[Copilot]

@copilot please use the StandardDirectory solution instead.

Implemented the StandardDirectory solution as requested. Replaced <Directory Id="TARGETDIR" Name="SourceDir" override="true"> with <StandardDirectory Id="ProgramFiles64Folder">, which uses WiX v4's modern approach and avoids the virtual symbol conflict entirely. This is more future-proof than the override attribute approach.

Changes in commit 35a3bed.