Fix: memory leak with when using Http(s)Agent keepAlive=true

[notanengineercom]

Fixes #390
This pull request contains:

• The spec to reproduce the memory leak condition and the fix
• Inverted logic for the sockets related event listener assignments. The event listeners only register if the specific hook is defined in the HTTP gatewayConfig object.

The spec fails without the fix: when keep-alive is enabled, the tcp socket events register twice (once per API call):

[test] 1) integration HTTP event callbacks keep alive
[test] Message:
[test] Expected 2 to be 1.
[test] Stack:
[test] at
[test] at Object.verifySockets (/Users/notanengineer/Documents/GitHub/mappersmith/spec/integration/node/support/keep-alive.js:13:46)
[test] at /Users/notanengineer/Documents/GitHub/mappersmith/spec/integration/node/integration.spec.js:95:27
[test] at processTicksAndRejections (node:internal/process/task_queues:96:5)
[test] Message:
[test] Expected 2 to be 1.
[test] Stack:
[test] at
[test] at Object.verifySockets (/Users/notanengineer/Documents/GitHub/mappersmith/spec/integration/node/support/keep-alive.js:14:47)
[test] at /Users/notanengineer/Documents/GitHub/mappersmith/spec/integration/node/integration.spec.js:95:27
[test] at processTicksAndRejections (node:internal/process/task_queues:96:5)
[test]
[test] 20 specs, 1 failure
[test] Finished in 0.819 seconds

[changeset-bot]

🦋 Changeset detected

Latest commit: d3ef379

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
mappersmith	Minor

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[allanpaiste]

@klippx @tulios perhaps you could find time to confirm the validity of this PR and get this merged/released? :)

[klippx]

Thanks for the PR, really great, I appreciate the effort! I hope you don't mind that I have some humble comments from my perspective, please give me your feedback and we can agree what makes sense and what does not. 🙏

[notanengineercom]

@klippx thanks for the great feedback and review, I really liked the suggestions. The only pending task is the test for the onRequestSocketAssigned callback I believe. Let me know if you have any other suggestions!
One thing I learnt: to not rush code after work 🙈

[klippx]

One thing I learnt: to not rush code after work 🙈

Don't worry, I appreciate that you got a PR up including test case and all, that's more than most people will put up!

Pending tasks

• Add test for the onRequestSocketAssigned callback

[notanengineercom]

Pending tasks

• Add test for the onRequestSocketAssigned callback

I didn't mention it in a comment, but yesterday I pushed a commit with the test for the onRequestSocketAssigned callback 😄