chore: unify toHaveScreenshot error formatting

[yury-s]

• Changed error header to align with other expect matchers
• Prepend timeout error message same way as in other matchers

New message:

[github-actions]

Test results for "tests 1"

3 flaky

⚠️ [playwright-test] › ui-mode-test-ct.spec.ts:215:5 › should watch component via util @ubuntu-latest-node20-1
⚠️ [webkit-library] › library/browsercontext-viewport-mobile.spec.ts:206:5 › mobile viewport › view scale should reset after navigation @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

36675 passed, 626 skipped
✔️✔️✔️

Merge workflow run.