Suggested test: copilot/submit-pull-request-review-self-authored-fallback

## Motivation

Link to the gh-aw PR: github/gh-aw#47400 — fix: downgrade REQUEST_CHANGES→COMMENT on self-authored PRs in safe-outputs PR review

When the reviewing identity matches the PR author, GitHub rejects `REQUEST_CHANGES` with 422 "Can not request changes on your own pull request". The fix ensures reviewer workflows fall back to `COMMENT` in this case. Previously the fallback was bypassed when another 422 ("Line could not be resolved") occurred first. There is no regression test for this scenario.

## Proposed test

- **Workflow file**: `test-copilot-submit-pull-request-review-self-authored-fallback.md`
- **Trigger**: `workflow_dispatch`
- **Engine**: copilot
- **Safe output**: `submit-pull-request-review`
- **Variant**: standard

## Minimal test prompt sketch

Dispatch a review against a pull request authored by the same bot identity running the workflow. Ask the agent to request changes. The test passes if the review is successfully submitted (as a COMMENT) rather than failing with a 422 error.

## New fixtures or secrets needed

Requires a PR in `githubnext/gh-aw-test` authored by the same bot/app identity that submits the review. This may require a dedicated fixture PR or a test-setup step that creates such a PR.

## Notes

The existing `test-copilot-submit-pull-request-review.md` and `test-copilot-submit-pull-request-review-locked.md` both use PRs authored by a different identity. A self-authored PR fixture is the key missing element.

> [!WARNING]
>
> Firewall blocked 1 domain
>
> The following domain was blocked by the firewall during workflow execution:
>
> - `awmgmcpg`
>> To allow these domains, add them to the `network.allowed` list in your workflow frontmatter:
>
> ```yaml
> network:
> allowed:
> - defaults
> - "awmgmcpg"
> ```
>
> See [Network Configuration](https://github.github.com/gh-aw/reference/network/) for more information.
>
>

> Generated by [🔍 Suggest New E2E Tests](https://github.com/githubnext/gh-aw-test/actions/runs/29994494559) · sonnet46 22.2 AIC · ⌖ 5.72 AIC · ⊞ 5.7K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-test+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-test%2Fsuggest-new-e2e-tests%22&type=issues)

先從 test-copilot-submit-pull-request-review.md 和 test-copilot-submit-pull-request-review-locked.md 開始，然後使用提議的 workflow 設定建立 test-copilot-submit-pull-request-review-self-authored-fallback.md。調查 githubnext/gh-aw-test 如何提供 PR fixture 和 bot identity credentials。當針對自己建立的 PR 執行由 workflow 分發的 review，並成功以 COMMENT 形式完成而不是以 422 失敗時，即視為完成。

由索引模型根據 Issue 內容生成。