src: refactor TimerWrap lifetime management

Split `Stop(true)` and `Stop(false)` into separate methods since the
actions performed by these are fully distinct.

PR-URL: https://github.com/nodejs/node/pull/34252


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: David Carlier <devnexen@gmail.com>