[CI Failure] Flaky: AppHostSdkTargetsTests full-framework MSBuild test times out locating MSBuild via vswhere.exe

## Build Information

Build: https://github.com/microsoft/aspire/actions/runs/32311965446
Build error leg or test failing: Tests / Build native CLI archive (macOS) / Build CLI (osx-arm64) / `Aspire.Hosting.Sdk.Tests.AppHostSdkTargetsTests.RunAspireCliCommandKillsCommandShimProcessTreeOnTimeoutInFullFrameworkMsBuild`
Pull request: #19501

## Error Message

```
System.TimeoutException : C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe -latest -products * -requires Microsoft.Component.MSBuild -find MSBuild\**\Bin\MSBuild.exe timed out after 00:00:30.
at Aspire.Hosting.Sdk.Tests.AppHostSdkTargetsTests.FindFullFrameworkMSBuildAsync()
```

## Description

Flaky: AppHostSdkTargetsTests full-framework MSBuild test times out locating MSBuild via vswhere.exe

**Type**: flaky-test

## Occurrences

| Date | Build | Job | PR |
|------|-------|-----|----|
| 2026-08-20 | [32311965446](https://github.com/microsoft/aspire/actions/runs/32311965446) | Tests / Build native CLI archive (macOS) / Build CLI (osx-arm64) | #19501 |
| 2026-08-24 | [32755490521](https://github.com/microsoft/aspire/actions/runs/32755490521) | Tests / Hosting.Valkey / Hosting.Valkey (ubuntu-latest) | #19613 |

Start with Aspire.Hosting.Sdk.Tests.AppHostSdkTargetsTests.RunAspireCliCommandKillsCommandShimProcessTreeOnTimeoutInFullFrameworkMsBuild and inspect FindFullFrameworkMSBuildAsync. Run the named test in the affected build contexts and investigate the 30-second vswhere.exe lookup timeout. Done means the test completes reliably without timing out while locating full-framework MSBuild.

Written by the indexing model from the issue text.