stream: remove redundant context from comments

Using the variable name in the comment and justifying the type seems
redundant to me and instead it should defined the entity which it is
acting, like in our case it is acting as a flag to control the flow in
streams.

PR-URL: https://github.com/nodejs/node/pull/35728


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>