test: unflake client-certificate WebKit tests

[mxschmitt]

Before it was failing with

Playwright client-certificate error: Hostname/IP does not match certificate's altnames: Host: local.playwright. is not cert's CN: localho

[Skn0tt]

Smart!

[github-actions]

Test results for "tests 1"

1 failed
❌ [playwright-test] › runner.spec.ts:118:5 › should ignore subprocess creation error because of SIGINT

6 flaky

⚠️ [chromium-library] › library/browsercontext-fetch-happy-eyeballs.spec.ts:49:3 › get should work on request fixture
⚠️ [chromium-library] › library/browsercontext-fetch-happy-eyeballs.spec.ts:49:3 › get should work on request fixture
⚠️ [firefox-library] › library/browsercontext-fetch-happy-eyeballs.spec.ts:49:3 › get should work on request fixture
⚠️ [chromium-library] › library/browsercontext-fetch-happy-eyeballs.spec.ts:49:3 › get should work on request fixture
⚠️ [playwright-test] › ui-mode-test-screencast.spec.ts:21:5 › should show screenshots
⚠️ [webkit-library] › library/browsercontext-fetch-happy-eyeballs.spec.ts:49:3 › get should work on request fixture

23934 passed, 616 skipped
✔️✔️✔️

Merge workflow run.