Revert "fix(client-certificates): reestablish a way to explicitly send no client certificate for an origin"

[Yury Semikhatsky (yury-s)]

Reverts #42547

Decided not to include it into the release as it is for negative testing and for that one can talk directly to the server from node as our client cert emulation is anyway in the node land and would not be an accurate representation of the browser behavior when a cert is missing.

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [chromium-library] › library/video.spec.ts:762 › screencast › should work with video+trace `@realtime-time-library-chromium-linux`
⚠️ [chromium-library] › library/video.spec.ts:762 › screencast › should work with video+trace `@chromium-ubuntu-22.04-node22`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:257 › third party 'Partitioned;' cookies `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:470 › top level 'Partitioned;' cookie and same origin iframe `@firefox-ubuntu-22.04-node20`

52507 passed, 1270 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

1 failed
❌ [chrome] › mcp/annotate.spec.ts:137 › should abort MCP annotation when last screenshot is removed @mcp-windows-latest-chrome

8936 passed, 1489 skipped

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Merge workflow run.

[github-actions]

🟢 The MCP failure is a pre-existing flake — this PR is clear

Hi, I'm the Playwright bot and I took a first look at the CI failure.

mcp/annotate.spec.ts:137 › should abort MCP annotation when last screenshot is removed has failed with the same thumbnail-count assertion on unrelated PRs, and a rerun on #42971 passed. This PR only reverts client-certificate handling and does not reach the MCP annotation dashboard.

Details

At head 1060f45d, the main test report has no failures. The only red result is the Windows Chrome MCP test below.

Pre-existing flake / infra

• [chrome] › mcp/annotate.spec.ts:137 › should abort MCP annotation when last screenshot is removed (mcp-windows-latest-chrome) — timed out waiting for .annotate-sidebar-thumb, receiving undefined instead of a count of 1 while dashboard navigation was still finishing. The same test and bot failed on unrelated test: JSHandle.getProperties() returns own properties only #42749 with the same expect(locator('.annotate-sidebar-thumb')).toHaveCount(1) assertion; prior CI history there recorded 2 failures and 709 passes. It failed again on unrelated fix(webkit): use native checkVisibility for element visibility #42971, whose rerun then passed with 8,790 passed and no failures. The revert here changes client-certificate types, validation, proxy interception, and their library tests; none of those paths are used by this MCP dashboard flow.

_{Triaged by the Playwright bot - agent run}