Description

This PR addresses the flaky 'lockdown' e2e test, specifically when running in Firefox, which is a tricky one.

Root Cause: The flakiness is caused by the rapid execution of the lockdown test script in Firefox immediately after navigating to the BACKGROUND page. This quick transition did not allow sufficient time for the environment to stabilize, preventing the script from accurately assessing the lockdown state.

Fix Implemented: To mitigate this issue, I introduced a await driver.delay(1000) after navigating to the BACKGROUND page and before executing the lockdown test script. This brief pause ensures that the environment is fully loaded and stable, allowing the script to run under consistent conditions and accurately verify the lockdown state.

While I'm agree that the use of delay should be minimized, this test's specific nature and the absence of a way to use the driver to wait for an element's status makes it necessary to use the delay() method.

Results:
Before the Fix: The flakiness could be reproduced locally on Firefox with approximately a 30% occurrence rate.
After the Fix: After implementing the changes, I ran the test 20 consecutive times without encountering any flakiness, demonstrating the effectiveness of the fix.

Related issues

Fixes: #24621

Manual testing steps

1. Run the test several times yarn test:e2e:single test/e2e/tests/request-queuing/ui.spec.js --browser=firefox --leave-running --retryUntilFailure --retries=10
2. Check ci jobs

Screenshots/Recordings

Before

After

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Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
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