[CI Failure] Flaky: NewUpAndBuildStandaloneTemplateTests.CanNewAndBuild(aspire-ts-cs-starter, Net11) fails building generated project on Windows with preview .NET 11 SDK

## Build Information

Build: https://github.com/microsoft/aspire/actions/runs/33902845984
Build error leg or test failing: Tests / No-package tests (regular, Aspire.Dashboard.Components.Tests, Dashboard.Components, Dashboard.Components (windows-latest)) / `Aspire.Templates.Tests.NewUpAndBuildStandaloneTemplateTests.CanNewAndBuild(templateName: "aspire-ts-cs-starter", extraArgs: "", sdk: Net11, tfm: Net10, error: null)`
Pull request: #19243

## Error Message

```
Aspire.Templates.Tests.ToolCommandException : Expected 0 exit code but got 1: dotnet.exe build ... /p:TreatWarningsAsErrors=true -c Debug /p:AspireUseCliBundle=false. Uses preview .NET 11 SDK 11.0.100-preview.6; unrelated to PR Kubernetes/Helm changes.
```

## Description

Flaky: NewUpAndBuildStandaloneTemplateTests.CanNewAndBuild(aspire-ts-cs-starter, Net11) fails building generated project on Windows with preview .NET 11 SDK

**Type**: flaky-test

## Occurrences

| Date | Build | Job | PR |
|------|-------|-----|----|
| 2026-09-04 | [33902845984](https://github.com/microsoft/aspire/actions/runs/33902845984) | Tests / No-package tests (regular, Aspire.Dashboard.Components.Tests, Dashboard.Components, Dashboard.Components (windows-latest)) | #19243 |

Start with Aspire.Templates.Tests.NewUpAndBuildStandaloneTemplateTests.CanNewAndBuild for the aspire-ts-cs-starter template and the Windows no-package test job. Reproduce the dotnet build using the preview .NET 11 SDK and inspect the generated project's build output; done means the reported Windows failure is understood and the test completes reliably.

Written by the indexing model from the issue text.