Use arrays in Ci::Pipeline#latest_builds_with_artifacts
What does this MR do?
This changes Ci::Pipeline#latest_builds_with_artifacts so it returns an Array instead of a relation, reducing the number of queries necessary to render the button for downloading CI artifacts. See the commit message for more details.
Does this MR meet the acceptance criteria?
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Changelog entry added, if necessary 
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Tests added for this feature/bug 
- Review
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Has been reviewed by Backend 
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Has been reviewed by Database 
 
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Conform by the merge request performance guides 
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Conform by the style guides 
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Squashed related commits together 
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Internationalization required/considered