src: remove process._inspectorEnbale

This commit removes process._inspectorEnbale which was
spelled incorrectly, and is being properly implemented
in a separate PR.

Refs: https://github.com/nodejs/node/pull/12949
PR-URL: https://github.com/nodejs/node/pull/13460


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luca Maraschi <luca.maraschi@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>