[CI Postmortem] 'Install dotnet workloads' failures causing cascading test failures

## Infrastructure Failure Report (automated)

**Failing Step:** `Install dotnet workloads`
**Period:** Apr 27 – May 4, 2026
**Occurrences:** 22 across 2 PRs (#24888, #25268)

### Error Messages

```
Bash exited with code '1'.
The task has timed out.
```

### Sample Occurrences

| PR | Build | Bot | Job | Direct Link |
|----|-------|-----|-----|-------------|
| #24888 | 13980424 | VSCXSDKs-MINI-016.Tahoe.arm64 | T: fsharp | [Install dotnet workloads](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=13980424&view=logs&j=d82aead2-6ee3-5699-e068-c63679dd04d9&t=65ef43ca-606b-53a4-b3ef-217a5d95b386) |
| #24888 | 13980424 | VSCXSDKs-MINI-049.Tahoe.arm64 | T: monotouch_macos | [Install dotnet workloads](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=13980424&view=logs&j=0564bbc5-6c6b-5cb4-3d05-9ed0b2c86721&t=ac444b41-ef56-5ee8-7214-5f1323e6c4e4) |
| #25268 | 13982584 | VSCXSDKs-MINI-066.Tahoe.arm64 | T: fsharp | [Install dotnet workloads](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=13982584&view=logs&j=d82aead2-6ee3-5699-e068-c63679dd04d9&t=65ef43ca-606b-53a4-b3ef-217a5d95b386) |
| #25268 | 13982584 | VSCXSDKs-MINI-032.Tahoe.arm64 | T: interdependent-binding-projects | [Install dotnet workloads](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=13982584&view=logs&j=423b2900-bf2a-55b5-1a4f-b15b829a55ad&t=bb4b01a5-f02a-536b-c271-24714c612833) |

### Impact

When workload installation fails or times out, the entire downstream test pipeline fails. This produces `Path does not exist` warnings on artifact publishing steps (which have `continueOnError: true`), but the root cause is this step.

---
*This issue was automatically generated by CI post-mortem analysis.*
*Split from #25263 which incorrectly attributed the failures to the downstream symptom.*