style-only: Remove redundant scope in *Chainstate

Summary:
Completes backport of core#23280:
https://github.com/bitcoin/bitcoin/pull/23280/commits/7f15eff2ddd86034e84a19413e1a42883987f660

Depends on D12584.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D12585