fix(test): attaching in boxed fixture

[Skn0tt]

Resolves #37147, which regressed in 5965db1. We're trying to report an attachment for a step that we skipped reporting, which leads to the error. The fix is to exclude the stepId when reporting the attachment.

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:1079 › cli codegen › should not throw csp directive violation errors `@firefox-ubuntu-22.04-node18`
⚠️ [firefox-page] › page/page-event-request.spec.ts:182 › should return response body when Cross-Origin-Opener-Policy is set `@firefox-ubuntu-22.04-node18`
⚠️ [firefox-page] › page/page-wait-for-function.spec.ts:104 › should work with strict CSP policy `@firefox-ubuntu-22.04-node18`
⚠️ [playwright-test] › ui-mode-test-output.spec.ts:117 › should collapse repeated console messages for test `@macos-latest-node18-1`

46630 passed, 805 skipped

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Merge workflow run.