[net] Remove unnecessary default args on CNode constructor

Summary:
Completes backport (19/19) of core PR19316:
https://github.com/bitcoin/bitcoin/pull/19316/commits/01e283068b9e6214f2d77a2f772a4244ebfe2274

Depends on D8728.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8729