fix(NODE-5993): memory leak in the Connection class

[nbbeeken]

Description

What is changing?

• Remove promise wrapping of signal
• Make writing async based on whether or not write returns true
• Remove signal

Is there new documentation needed for these changes?

What is the motivation for this change?

The Connection class stored a promise that would reject when the signal was aborted. This caused a leak that would create new promises unbounded. I've removed the promise wrapping opting for a simpler implementation that only makes writing async if there was buffering. If there was buffering we wait for the drain event and use try/finally to make sure we clean up event listeners.

Release Highlight

Fixed memory leak in Connection layer

The Connection class has recently been refactored to operate on our socket operations using promises. An oversight how we made async network operations interruptible made new promises for every operation. We've simplified the approach and corrected the leak.

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
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• Changes are covered by tests
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