Bump timeouts for new WebView tests

[johnzhou721]

I've seen that some of the tests I'm hereby marking with @pytest.mark.flaky(retries=5, delay=1) has failed on the main branch. Given that CI's machine is very slow, I've bumped some timeouts and added a flaky mark as a defensive measure (to reduce intermittnet failures.)

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[johnzhou721]

I was specifically talking about the failures in this run.

Also -- I am aware that core team mebers are on leave and may not respond for up to 8 days.

[HalfWhitt]

I'm not at all familiar with what #3973's doing, but this seems reasonable to me, and hey, it's passing! 😃

[freakboy3742]

This is a good immediate workaround; however probe.redraw(... delay=5) has a longer term problem - it means the test actually takes 5 seconds to run. This change has increased the runtime for the test suite by at least 18 seconds. What we need here is a timeout, not a hard delay.