[CI Failure] VS Code extension E2E tests fail to download aspire-extension VSIX artifact after upstream packaging job failed

## Build Information

Build: https://github.com/microsoft/aspire/actions/runs/33086828076
Build error leg: Tests / Run VS Code extension unit tests (Windows)
Pull request: #19730

## Error Message

```
Unable to download artifact(s): Artifact not found for name: aspire-extension. Please ensure that your artifact is not expired and the artifact was uploaded using a compatible version of toolkit/upload-artifact. Cascading failure from the upstream 'Run VS Code extension unit tests (Windows)' job which failed to produce the VSIX.
```

## Description

VS Code extension E2E tests fail to download aspire-extension VSIX artifact after upstream packaging job failed

**Type**: infra-failure

## Occurrences

| Date | Build | Job | PR |
|------|-------|-----|----|
| 2026-08-27 | [33086828076](https://github.com/microsoft/aspire/actions/runs/33086828076) | Tests / Run VS Code extension unit tests (Windows) | #19730 |
| 2026-09-08 | [34259343802](https://github.com/microsoft/aspire/actions/runs/34259343802) | Tests / Run VS Code extension unit tests (Windows) / Run VS Code extension unit tests (Windows) | #17742 |

Start with workflow run 33086828076 and the Tests / Run VS Code extension unit tests (Windows) job, then inspect the upstream packaging job and its VSIX artifact upload and download steps. Compare the occurrences from runs 33086828076 and 34259343802; done means the packaging job produces aspire-extension and the Windows E2E tests can download it successfully.

Written by the indexing model from the issue text.