[ci] Use repo NuGet config for template smoke build

[jonathanpeppers]

Why

Depends on #12336.

The Windows template smoke project is generated under $(Build.StagingDirectory), outside the repository NuGet.config hierarchy. Its implicit build restore therefore falls back to the agent's machine NuGet configuration and may access unapproved package feeds.

#12336 disables NuGet auditing pipeline-wide. This dependent change keeps the smoke build's restore on the repository's approved sources.

Changes

• Pass RestoreConfigFile=$(System.DefaultWorkingDirectory)\NuGet.config to the template build.
• Quote the template creation and build staging paths using Windows path syntax.

Validation

• Parsed build-windows-steps.yaml successfully.

• Ran git diff --check.

• Verified the Windows create and build commands with generated project paths containing spaces.

• Verified restore used only the repository NuGet.config feeds and binlogtool reported the expected RestoreConfigFile.

• Useful description of why the change is necessary.

• Links to issues fixed (depends on [ci] Prevent isolated NuGet access #12336; no GitHub issue).

• Unit tests (not applicable to pipeline-only YAML; targeted validation listed above).

[Copilot]

Pull request overview

Updates the Windows CI template smoke-build step to ensure restores use the repository-approved NuGet sources even when the generated project lives outside the repo’s NuGet.config hierarchy, avoiding reliance on the agent’s machine-level NuGet configuration.

Changes:

• Passes -p:RestoreConfigFile=...NuGet.config to the template dotnet build to force repository NuGet source usage.
• Quotes the staging-directory project path for the build invocation and switches to Windows-style path separators.

---

💡 Add a code-review agent skill for context-aware, tailored reviews. Learn more in the docs.

[jonathanpeppers]

@dalexsoto review

[dalexsoto]

Reviewed the current changes. NuGet config propagation, quoting, working directories, approved-feed isolation, and public/internal pipeline parity look correct. No blocking issues found.

[dalexsoto]

The current head only updates the base; the workflow change remains identical to the previously approved revision, and the NuGet config propagation and Windows path quoting are still correct. No blocking issues found.

[jonathanpeppers]

Test failure is unrelated.

[jonathanpeppers]

@dalexsoto review

[dalexsoto]

Re-reviewed the current context. The workflow diff remains byte-identical to the approved revision, and the repository NuGet configuration and Windows path quoting remain correct. No blocking issues found.