chore(NODE-7833): 'latest' server binary behind s3

[johnmtll]

Description

Summary of Changes

1. Updates Evergreen config to assume the necessary role to retrieve the nightly server build (latest) which is now behind a private S3 bucket.
2. Updates local integration test run documentation to note aws profile setup as a prerequisite, and callout that omitting the VERSION will pull latest-stable instead of latest.
3. Various tests are incompatible with v20/v12 of ubuntu/debian given the latest DET changes, these tests have been updated to use a later version.

Notes for Reviewers

• AWS Profile setup tested as a prerequisite for pulling latest.

Double check the following

• Lint is passing (npm run check:lint)
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[Copilot]

🟡 Changes recommended

The local testing guide incorrectly presents internal AWS access as mandatory for stable server builds.

1 open finding

• Scope AWS access prerequisite to VERSION='latest' · New

What changed in this PR

Adds AWS role access for nightly MongoDB binaries and documents local setup.

Changes:

• Assumes the required AWS role in Evergreen.
• Documents nightly versus stable server setup.

File	Description
.evergreen/​config.in.yml	Adds role assumption to source config.
.evergreen/​config.yml	Updates generated Evergreen config.
test/​readme.md	Documents local AWS setup and version defaults.
AGENTS.md	Updates integration-test guidance.

🧠 Review effort: Balanced

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[PavelSafronov]

Changes look good and CI is green, approving!

[tadjik1]

Thanks @johnmtll !