feat(node-http-handler): defer socket event listener attachment

[kuhe]

aws/aws-sdk-js-v3#6423

This PR defers the registration of socket event listeners on individual requests outgoing from node:http(s) requests.

Attaching events creates a small performance overhead (0-2ms) and I believe they are unnecessary for requests that resolve in under 3 seconds for timeouts of greater than 6 seconds.

Here is a comparison of the use-case of a request before and after this PR:

Before PR

• request is created
• socket event listeners are attached
• request is submitted
• socket event triggers event listeners
  • some don't do anything because the timeouts involved are far higher than the request duration
  • sending a keepalive probe is useless if the request completes in e.g. under a second
• request completes, event listeners are cleaned up

After PR

• request is created
• no event listeners register until the request duration exceeds 3 seconds or the configured timeout is less than 6 seconds, in which case they are still immediately registered.
  • avoids sending keepalive probe too early for short duration request
  • avoids adding other socket event listeners until needed
• request is submitted
• request completes, event listeners are cleaned up, or event listener deferment timeouts are cleared