gui: Drop PeerTableModel dependency to ClientModel

Summary:

Class PeerTableModel doesn't actually depend on ClientModel.

This removes the circular dependency qt/clientmodel -> qt/peertablemodel -> qt/clientmodel

This is a backport of Core PR18060

Test Plan:
ninja && src/qt/bitcoin-qt

PeerTableModel is used in the rpc console GUI.

test/lint/lint-circular-dependencies.sh

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D8737