Disable shared compilation when building wslsettings

[OneBlue]

Summary of the Pull Request

This change attempts to fix a recurring build error that the release pipeline hits when building wslsettings (CS0016).

I'm not 100% certain that this will resolve the issue, but it's worth trying. Will revert if we still see it after this is merged

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[Copilot]

Pull request overview

This PR attempts to mitigate intermittent Roslyn build failures (CS0016) in the release pipeline when building wslsettings by disabling the shared compilation server (VBCSCompiler) via an MSBuild property.

Changes:

• Add an MSBuild PropertyGroup setting UseSharedCompilation=false for the wslsettings build.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.