refactor: Rename Node::disconnect methods

Summary:
Avoid overloading method name to work more easily with IPC framework

Backport of Core PR18278 part [2/6] : https://github.com/bitcoin/bitcoin/pull/18278/commits/1c2ab1a6d29f2c6c065dae4f4a4e2ad1286311b3

Depends on D8019

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D8020