test: revert "test: set defaultBrowser to chrome (#1713)"

[MikeMcC399]

Situation

Workflows recording to Cypress Cloud are currently sporadically failing due to a deployment of ubuntu-24.04

This includes a major version update from Google Chrome 146 to 147.

Category	Tool name	Previous (20260406.80.1)	Current (20260413.86.1)
Browsers and Drivers	Google Chrome	146.0.7680.177	147.0.7727.55
	ChromeDriver	146.0.7680.165	147.0.7727.56
	Chromium	146.0.7680.0	147.0.7727.0
	Microsoft Edge	146.0.3856.97	147.0.3912.60
	Microsoft Edge WebDriver	146.0.3856.97	147.0.3912.60
	Selenium server	4.41.0	4.43.0
	Mozilla Firefox	149.0	149.0.2

This is a known issue described in the README > parallel section:

During staged rollout of a new GitHub-hosted runner version, GitHub may provide a mixture of current and new image versions used by the container matrix. It is recommended to use a Docker image in the parallel job run which avoids any Cypress Cloud errors due to browser major version mismatch from the two different image versions. A Docker image is not necessary if testing against the default built-in Electron browser because this browser version is fixed by the Cypress version in use and it is unaffected by any GitHub runner image rollout.

In anticipation of a change in the future Cypress 16 release, which would have removed Electron as the default browser, PR #1713 set Chrome as the default browser in this repo.

In the meantime, the plans for Cypress 16 have changed and Electron remains.

Setting Chrome as default has exposed the workflows to the issue described above, where GitHub Actions randomly provides old and new runner versions in parallel runs.

Change

Revert #1713 commit 68be0d4 to reset the default browser version from an explicit choice of Chrome back to Cypress' default setting of Electron.

---

Note

Low Risk
Changes are limited to CI/test configuration and browser selection; main risk is unintended shifts in which browser tests run under (especially in existing workflows) rather than production behavior.

Overview
Reverts the examples’ Cypress configuration to stop forcing defaultBrowser: 'chrome', letting Cypress fall back to its default browser (Electron) to reduce flakiness from GitHub runner Chrome version drift.

Updates the example-docker GitHub Actions workflow matrix to also run tests against electron alongside chrome, edge, and firefox.

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[cypress-app-bot]

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[MikeMcC399]

The yarn-modern-pnp CI failure is separately fixed in PR #1728