[7.x] [ML] Add UI test for feature importance features (#82677)

[qn895]

Backports the following commits to 7.x:

• [ML] Add UI test for feature importance features ([ML] Add UI test for feature importance features #82677)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: e92456c

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
ml	5.2MB	5.2MB	+638.0B

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@elasticmachine merge upstream