Add 1/2 second sleep to fix test

[LeeDr]

Summary

Fixes: #22299

The test is "dashboard app using current data dashboard view edit mode shows lose changes warning and loses changes on confirmation when a new vis is added"
in test\functional\apps\dashboard\view_edit.js

This PR adds a 1/2 second sleep in between clicking cancel from edit mode on a dashboard and the click to confirm that cancel. Although this test usually passes on Jenkins, I've never had it pass for me locally using either Chrome or Firefox browser. With the small sleep it always passes for me. Without the sleep, it looks like the cancel doesn't happen. The 3rd panel added to the dashboard is still there and so the test fails with Error: expected 3 to sort of equal 2

I think it's actually a product bug. My thought is that the confirm cancel modal dialog appears and the test is clicking confirm before some event handler is attached to the button? But since real users won't ever click it that fast, I think it's OK to just fix this test.

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

- [ ] This was checked for cross-browser compatibility, including a check against IE11
- [ ] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
- [ ] Documentation was added for features that require explanation or tutorials

• Unit or functional tests were updated or added to match the most common scenarios
  - [ ] This was checked for keyboard-only and screenreader accessibility

For maintainers

- [x] This was checked for breaking API changes and was labeled appropriately
- [] This includes a feature addition or change that requires a release note and was labeled appropriately

[dmlemeshko]

@LeeDr What if you try await renderable.waitForRender(); in place of sleep?
I wonder if data-render-complete attribute is changing at the moment and we can use it.

Otherwise, I'm good with sleep :)

[elasticmachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request

[LeeDr]

@dmlemeshko see comments back on this issue #22299

I don't know if we wait for the modal dialog to render? I don't know if there's something in the DOM we can check to know when it's ready.

[dmlemeshko]

I checked it locally and agree with the proposed solution

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[LeeDr]

@stacey-gammon I'm not sure where you are on investigating this issue, but I'm going to go ahead and merge this one-line temporary work-around to get the test passing. When we figure out why the cancel changes isn't working we can remove this sleep.

[stacey-gammon]

Thanks @LeeDr, I have no time to investigate, so sg to stabilize tests.