wallet: IsChange requires cs_wallet lock

Summary:
This is a backport of core#19289 [3/3]
https://github.com/bitcoin/bitcoin/pull/19289/commits/b8405b833ad28351c80fb10f6f896f974013fd9e

Depends on D10096

Test Plan:
With Clang and Debug:
ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10097