test: refactor http pipelined socket test

In test-http-incoming-pipelined-socket-destory:

* setTimeout() with no duration -> setImmediate()
* eliminate unneeded exit listener
* use common.mustCall()
* var -> const/let

PR-URL: https://github.com/nodejs/node/pull/10189


Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>