[CI Failure] Flaky: XUnit_V2_NewUpAndBuildSupportProjectTemplatesTests.CanNewAndBuild times out after 300s running 'dotnet new aspire-apphost' on Windows runner

## Build Information

Build: https://github.com/microsoft/aspire/actions/runs/31728585505
Build error leg or test failing: Tests / Polyglot SDK Validation / TypeScript SDK Validation (Node 24.x) / `Aspire.Templates.Tests.XUnit_V2_NewUpAndBuildSupportProjectTemplatesTests.CanNewAndBuild`
Pull request: #19077

## Error Message

```
System.Threading.Tasks.TaskCanceledException : Command execution timed out after 300 secs: 'D:\a\aspire\aspire\artifacts\bin\dotnet-8\dotnet.exe new aspire-apphost -o "new_build_aspire_xunit_..." -f net9.0 --debug:custom-hive ...' at Aspire.Templates.Tests.ToolCommand.ExecuteAsync
```

## Description

Flaky: XUnit_V2_NewUpAndBuildSupportProjectTemplatesTests.CanNewAndBuild times out after 300s running 'dotnet new aspire-apphost' on Windows runner

**Type**: flaky-test

## Occurrences

| Date | Build | Job | PR |
|------|-------|-----|----|
| 2026-08-13 | [31728585505](https://github.com/microsoft/aspire/actions/runs/31728585505) | Tests / Polyglot SDK Validation / TypeScript SDK Validation (Node 24.x) | #19077 |

Start with Aspire.Templates.Tests.XUnit_V2_NewUpAndBuildSupportProjectTemplatesTests.CanNewAndBuild and the reported ToolCommand.ExecuteAsync timeout while running `dotnet new aspire-apphost`. Reproduce the 300-second timeout on the Windows validation runner and inspect the command's template-build path. Done means the test completes reliably without timing out in the affected validation job.

Written by the indexing model from the issue text.