net: simplify Socket.prototype._final

Remove conditions that should be irrelevant since we started
using `_final`, as well as an extra `defaultTriggerAsyncIdScope()`
call which is unnecessary because there is an equivalent
scope already present on the native side.

PR-URL: https://github.com/nodejs/node/pull/24075


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>