[8.x] [React@18] Refactor overview.tsx test to rtl (elastic#206805) (e…

…lastic#206916)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[React@18] Refactor overview.tsx test to rtl
(elastic#206805)](elastic#206805)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Anton
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Refactor overview.tsx test to rtl (elastic#206805)\n\n##
Summary\r\n\r\nExtracted from
https://github.com/elastic/kibana/pull/206411\r\n[[job]](https://buildkite.com/elastic/kibana-pull-request/builds/267344#019469ff-7fb9-4c5d-8569-2e445aab27be)\r\n[[logs]](https://buildkite.com/organizations/elastic/pipelines/kibana-pull-request/builds/267344/jobs/019469ff-7fb9-4c5d-8569-2e445aab27be/artifacts/01946a1c-62fa-4d30-8863-1b40f8c0b924)\r\nJest
Tests elastic#9 / Overview renders correctly when there is no user
data\r\nview\r\nThis simplifies overview.tsx by refactoring to rtl and
removing the\r\nwhole snapshot. The snapshot was not useful and the test
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By removing enzyme,\r\nthe test now works properly for both react 17 and
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Refactor overview.tsx test to
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Refactor overview.tsx test to rtl (elastic#206805)\n\n##
Summary\r\n\r\nExtracted from
https://github.com/elastic/kibana/pull/206411\r\n[[job]](https://buildkite.com/elastic/kibana-pull-request/builds/267344#019469ff-7fb9-4c5d-8569-2e445aab27be)\r\n[[logs]](https://buildkite.com/organizations/elastic/pipelines/kibana-pull-request/builds/267344/jobs/019469ff-7fb9-4c5d-8569-2e445aab27be/artifacts/01946a1c-62fa-4d30-8863-1b40f8c0b924)\r\nJest
Tests elastic#9 / Overview renders correctly when there is no user
data\r\nview\r\nThis simplifies overview.tsx by refactoring to rtl and
removing the\r\nwhole snapshot. The snapshot was not useful and the test
is still making\r\nsure that the intended component is still rendered.
By removing enzyme,\r\nthe test now works properly for both react 17 and
18.","sha":"bdcad52cd8d1569590107a43e3bea7cf25164af9"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.0.0","branchLabelMappingKey":"^v9.0.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/206805","number":206805,"mergeCommit":{"message":"[React@18]
Refactor overview.tsx test to rtl (elastic#206805)\n\n##
Summary\r\n\r\nExtracted from
https://github.com/elastic/kibana/pull/206411\r\n[[job]](https://buildkite.com/elastic/kibana-pull-request/builds/267344#019469ff-7fb9-4c5d-8569-2e445aab27be)\r\n[[logs]](https://buildkite.com/organizations/elastic/pipelines/kibana-pull-request/builds/267344/jobs/019469ff-7fb9-4c5d-8569-2e445aab27be/artifacts/01946a1c-62fa-4d30-8863-1b40f8c0b924)\r\nJest
Tests elastic#9 / Overview renders correctly when there is no user
data\r\nview\r\nThis simplifies overview.tsx by refactoring to rtl and
removing the\r\nwhole snapshot. The snapshot was not useful and the test
is still making\r\nsure that the intended component is still rendered.
By removing enzyme,\r\nthe test now works properly for both react 17 and
18.","sha":"bdcad52cd8d1569590107a43e3bea7cf25164af9"}}]}] BACKPORT-->

Co-authored-by: Anton Dosov <[email protected]>