bench: Add wallet_balance benchmarks

Summary:
This is a partial backport of Core PR15779 : https://github.com/bitcoin/bitcoin/pull/15779/commits/fa46ac3127142358116c8473741708b3bb70ca15

Also include pieces of PR15788 that previously were ignored becauseit was dead code.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D6236