[ci] Fail fast and retry transient failures on 'extract workload packs' (#11816)

When `extract workload packs` fails (e.g. a transient `dotnet workload install` network error), the step inherits `run-dotnet-preview.yaml`'s `continueOnError: true` default, so it's marked `succeededWithIssues` rather than failed. The job then boots the emulator and runs the entire device-test suite against a broken/rolled-back SDK, surfacing a pile of cascade "build failure" results (~19 in build 1486425) before finally failing at the very end.

## Changes

`build-tools/automation/yaml-templates/setup-test-environment-steps.yaml` — the `extract workload packs` step now overrides the template defaults to treat workload-pack extraction as a hard prerequisite:

```yaml
- template: /build-tools/automation/yaml-templates/run-dotnet-preview.yaml
  parameters:
    displayName: extract workload packs
    ...
    continueOnError: false       # fail the job immediately instead of succeededWithIssues
    retryCountOnTaskFailure: 2    # retry transient network blips (e.g. Connection reset by peer)
```

- **Fail fast** — `continueOnError: false` stops the job at setup with a clear error instead of running a doomed emulator suite and failing at the end.
- **Retry transient failures** — `retryCountOnTaskFailure: 2` retries one-off download errors before poisoning the run.

This mirrors the adjacent `install OpenJDK and accept Android SDK licenses` step, which already sets `continueOnError: false`.

Co-authored-by: simonrozsival <374616+simonrozsival@users.noreply.github.com>

Author: Copilot

build-tools/automation/yaml-templates/setup-test-environment-steps.yaml

@@ -103,6 +103,8 @@ steps:
     xaSourcePath: ${{ parameters.xaSourcePath }}
     project: ${{ parameters.xaSourcePath }}/build-tools/create-packs/Microsoft.Android.Sdk.proj
     arguments: -t:ExtractWorkloadPacks -c ${{ parameters.configuration }} -v:n -bl:${{ parameters.xaSourcePath }}/bin/Test${{ parameters.configuration }}/extract-workloads.binlog
+    continueOnError: false
+    retryCountOnTaskFailure: 2
 
 - ${{ if eq(parameters.installApkDiff, true) }}:
   - template: /build-tools/automation/yaml-templates/install-dotnet-tool.yaml