test(NODE-6766): skip serverless tests

[durran]

Description

Disables serverless testing.

What is changing?

Comment out the serverless variant in CI.

Is there new documentation needed for these changes?

None

What is the motivation for this change?

NODE-6766

Double check the following

• Ran npm run check:lint script
• 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