http: prevent aborted event when already completed

Tests in progress to reproduce issue consistently.

Fixes: https://github.com/nodejs/node/issues/18756

PR-URL: https://github.com/nodejs/node/pull/18999


Reviewed-By: Shingo Inoue <leko.noor@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>