Dead code removal
Summary:
- benchmark: Removed bench/perf.cpp
- node: Removed unused wallet-related methods from the Node interface.
This is a backport of Core PR13025
Test Plan:
make check make bench
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D3349