Update testing.md (#34661)

https://playwright.dev/docs/ci#running-headed
Playwright runs headless by default.



## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `yarn lint`

docs/testing.md

@@ -232,7 +232,7 @@ Run `npm run build` and `npm run start`, then run `npm run test:e2e` in another
 
 ### Running Playwright on Continuous Integration (CI)
 
-Playwright will by default run your tests in the [headed mode](https://playwright.dev/docs/ci). To install all the Playwright dependencies, run `npx playwright install-deps`.
+Playwright will by default run your tests in the [headless mode]https://playwright.dev/docs/ci#running-headed). To install all the Playwright dependencies, run `npx playwright install-deps`.
 
 You can learn more about Playwright and Continuous Integration from these resources: