Improving way to check if pipelines list is loaded

[dmlemeshko]

Summary

Part of #32385 fixes
Sometimes pipelines table is present without content and it causes test to fail. Adding check that loadingPipelines div is not present before we try to get table content.

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

- [ ] 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

[elasticmachine]

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[elasticmachine]

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[dmlemeshko]

retest

[elasticmachine]

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

Now we have a proper waiting in place 💪

[00:02:15]                 │ debg Waiting up to 20000ms for pipline list visible on screen...
[00:02:15]                 │ debg TestSubjects.find(pipelineList)
[00:02:15]                 │ debg Find.findByCssSelector('[data-test-subj~="pipelineList"]') with timeout=10000
[00:02:15]                 │ debg TestSubjects.exists(loadingPipelines)
[00:02:15]                 │ debg Find.existsByDisplayedByCssSelector('[data-test-subj~="loadingPipelines"]') with timeout=2500
[00:02:17]                 │ debg Waiting up to 20000ms for pipline list visible on screen...
[00:02:17]                 │ debg TestSubjects.find(pipelineList)
[00:02:17]                 │ debg Find.findByCssSelector('[data-test-subj~="pipelineList"]') with timeout=10000
[00:02:17]                 │ debg TestSubjects.exists(loadingPipelines)
[00:02:17]                 │ debg Find.existsByDisplayedByCssSelector('[data-test-subj~="loadingPipelines"]') with timeout=2500

[dmlemeshko]

retest

[elasticmachine]

💚 Build Succeeded

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[dmlemeshko]

retest

[elasticmachine]

💚 Build Succeeded

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

[dmlemeshko]

retest

[elasticmachine]

💚 Build Succeeded

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

[dmlemeshko]

100 (5 builds * 20 ) runs passed, I think it's good enough.

[elasticmachine]

💚 Build Succeeded

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

[cuff-links]

Ran 10x. Works and LGTM.

[dmlemeshko]

Backported
7.0 737b544
7.x 43344f1