chore: remove browser.on('context') event

[Dmitry Gozman (dgozman)]

Synchronous event promotes error-prone patterns.

[github-actions]

Test results for "tests 1"

3 failed
❌ [default] › run-tests.spec.ts:1305:5 › should provide page snapshot to copilot vscode-extension (@vscode-extension)
❌ [default-reuse] › run-tests.spec.ts:1305:5 › should provide page snapshot to copilot vscode-extension (@vscode-extension)
❌ [default-trace] › run-tests.spec.ts:1305:5 › should provide page snapshot to copilot vscode-extension (@vscode-extension)

10 flaky

⚠️ [chromium-library] › library/browsercontext-reuse.spec.ts:256:1 › should work with clock emulation @chromium-ubuntu-22.04-node18
⚠️ [chromium-library] › library/browsercontext-reuse.spec.ts:256:1 › should work with clock emulation @chromium-ubuntu-22.04-node20
⚠️ [chromium-library] › library/browsercontext-reuse.spec.ts:256:1 › should work with clock emulation @chromium-ubuntu-22.04-node22
⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:986:7 › cli codegen › should not throw csp directive violation errors @firefox-ubuntu-22.04-node18
⚠️ [firefox-library] › library/inspector/cli-codegen-pick-locator.spec.ts:35:7 › should update locator highlight @firefox-ubuntu-22.04-node18
⚠️ [firefox-page] › page/page-wait-for-function.spec.ts:104:3 › should work with strict CSP policy @firefox-ubuntu-22.04-node18
⚠️ [chromium-library] › library/browsercontext-reuse.spec.ts:256:1 › should work with clock emulation @ubuntu-22.04-chromium-tip-of-tree
⚠️ [webkit-library] › library/ignorehttpserrors.spec.ts:30:3 › should isolate contexts @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › page/page-screenshot.spec.ts:345:5 › page screenshot › should work while navigating @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

39271 passed, 818 skipped
✔️✔️✔️

Merge workflow run.