feat(NODE-5190)!: remove deprecated keep alive options

[durran]

Description

Remove the deprecated keep alive options.

What is changing?

• Removes the keepAlive and keepAliveInitialDelay options.
• Sets TCP keep alive to 30000 on the socket.

Is there new documentation needed for these changes?

None

What is the motivation for this change?

NODE-5190

Release Highlight

The deprecated keepAlive and keepAliveInitialDelay options have been removed.

TCP keep alive will always be on and now set to a value of 30000ms.

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