[CI Failure] .NET install script download fails with SSL/TLS authentication error from builds.dotnet.microsoft.com on Windows runner

Nobody has claimed this yet.

## Build Information

Build: https://github.com/microsoft/aspire/actions/runs/29612218857
Build error leg: Tests / Prepare Homebrew installer artifacts / Prepare Homebrew cask
Pull request: #18678

## Error Message

```
D:\a\aspire\aspire\tests\Shared\InstallSdk.targets(37,5): error MSB3923: Failed to download file "https://builds.dotnet.microsoft.com/dotnet/scripts/v1/dotnet-install.ps1". The SSL connection could not be established, see inner exception. ---> Authentication failed, see inner exception. ---> The Local Security Authority cannot be contacted
```

## Description

.NET install script download fails with SSL/TLS authentication error from builds.dotnet.microsoft.com on Windows runner

**Type**: infra-failure

## Occurrences

| Date | Build | Job | PR |
|------|-------|-----|----|
| 2026-07-17 | [29612218857](https://github.com/microsoft/aspire/actions/runs/29612218857) | Tests / Prepare Homebrew installer artifacts / Prepare Homebrew cask | #18678 |

Start with tests/Shared/InstallSdk.targets at line 37 and inspect the failing run 29612218857, especially the Tests / Prepare Homebrew installer artifacts / Prepare Homebrew cask job. Determine why the Windows runner cannot download dotnet-install.ps1 from builds.dotnet.microsoft.com, and consider the issue complete when this CI job can prepare the artifacts successfully.

Written by the indexing model from the issue text.