[WIP] Investigate and fix random hangs and crashes in Selenium tests

[Claude]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>[bug] Investigate random hangs and crashes in Selenium tests with websockets on GitHub Actions</issue_title>
<issue_description>Describe the bug
The test suite intermittently fails on GitHub Actions, specifically with tests involving websockets. Upon investigation, when running Selenium-based tests, they randomly hang and then crash with a ReadTimeoutError. This typically occurs when the Selenium Python client sends a command to ChromeDriver but never receives a response back. It appears the ChromeDriver process hangs without feedback, which leads to test failures.

This has impacted the ability to reliably run end-to-end or integration tests in CI. The issue was observed and discussed in PR openwisp/docker-openwisp#581, where the failing tests were removed temporarily to allow the CI to pass.

Steps To Reproduce
Steps to reproduce the behavior:

1. Run the Selenium test suite in GitHub Actions, especially tests relying on websockets
2. Observe intermittent test hangs and failures
3. Check the logs for ReadTimeoutError from Selenium
4. Note that the process never gets a response from ChromeDriver

Expected behavior
After adding back the tests removed in #581, all Selenium-driven tests (including those that use websockets) should complete without any unexplained timeout or hang. ChromeDriver should remain responsive and receive/respond to all commands.

• OS: Ubuntu (GitHub Actions latest runner)
• Docker version: Please specify from CI logs
• Browser and Browser Version (if applicable): Chrome (specify from CI logs)

Reference: The failing tests were removed in PR openwisp/docker-openwisp#581 due to this issue. Please investigate and propose a robust solution to enable reliable websocket testing in CI.</issue_description>

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