CLOUDP-313568: Adjust cluster instances to bypass Atlas slowness

[helderjs]

Summary

Atlas QA has been slower than usual for the past weeks and this is causing out tests to timeout and the CI pipeline to fail. This tweaks some instance sizes of timing out tests suggests by SREs

Proof of Work

CI Should be green.

Checklist

• Have you linked a jira ticket and/or is the ticket in the title?
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• Have you checked for release_note changes?
• Have you signed our CLA?

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