test(NODE-6820): test on Graviton processor

[tadjik1]

Description

Summary of Changes

Adds a new Evergreen build variant (amazon-linux-2023-arm64-graviton4) that runs the driver test suite on AWS Graviton 4 (arm64) hardware using the amazon2023-arm64-latest-large-m8g distro.

Tests included:

• All three topologies: standalone, replica set, sharded cluster (latest server)
• Native modules: zstd compression, snappy compression, mongo-client-encryption (CSFLE)

Kerberos testing is out of scope for this PR per NODE-6820.

Notes for Reviewers

The distro amazon2023-arm64-latest-large-m8g was identified in DRIVERS-2436 as the recommended Graviton 4 distro for integration testing (Graviton 4, AL2023).

The new Graviton4 AL2023 Node24 build variant is visible in Evergreen.

What is the motivation for this change?

ARM processors have known behavioral differences from x86 that can cause subtle bugs in native code - most notably, char is unsigned by default on ARM (vs. signed on x86), and floating-point contraction behavior may differ between gcc and clang. MongoDB servers on Graviton are increasingly common in Atlas, making it important to validate that our native driver modules (kerberos, snappy, zstd, CSFLE) behave correctly on this architecture.

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