[7.7][Discover] Fix flaky suites in _field_visualize

[sulemanof]

Summary

Resolves #61714

This is almost the same as #62418,
but a css selector was changed in clickFieldListItemVisualize :

 const field = await testSubjects.find(`field-${fieldName}`);

because of the discover sidebar was moved to react in 7.x and selectors changed a bit,
so the backport was not suitable : #62547

Checklist

Delete any items that are not applicable to this PR.

• 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
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• This was checked for cross-browser compatibility, including a check against IE11

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: ade988a

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@elasticmachine merge upstream

[nreese]

lgtm
code review

[dmlemeshko]

Code LGTM, tests are passing locally on the latest Firefox and Chrome (MacOS 10.14.6)