CLOUDP-338724: Support AKO 2.10

[josvazg]

Proposed changes

Make the plugin support AKO 2.10

Also:

• Consolidate most test version references as "latest", so we do not need to update them individually after each major release.
• Remove test and associated helpers for deprecated functionality, gone with version 2.7 for which this bump drops support for.
• Fix the installer's deploy URLs to use the new per release version paths: Since version 2.10.0 it is now releases/vX.Y.Z/deploy/instead of just deploy/.

Jira ticket: CLOUDP-338724

Checklist

• I have signed the MongoDB CLA
• [] I have added tests that prove my fix is effective or that my feature works
• I have added any necessary documentation in the document requirements section listed in CONTRIBUTING.md (if appropriate)
• I have addressed the @mongodb/docs-cloud-team comments (if appropriate)
• I have run make fmt and formatted my code

[helderjs]

LTGM if CI is green