test: vendor 'proxy' dependency

[mxschmitt]

Fixes #28701

[github-actions]

Test results for "tests 1"

1 failed
❌ [playwright-test] › watch.spec.ts:564:5 › should run CT on changed deps

4 flaky

⚠️ [chromium] › page/page-event-request.spec.ts:110:3 › should report navigation requests and responses handled by service worker
⚠️ [chromium] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks
⚠️ [firefox] › library/emulation-focus.spec.ts:65:3 › should not affect mouse event target page
⚠️ [chromium] › library/tracing.spec.ts:243:5 › should not include trace resources from the previous chunks

26539 passed, 615 skipped
✔️✔️✔️

Merge workflow run.

[yury-s]

Not sure if the tests worth copying the dependency, I'd probably just disable them for now. Up to you.