validation: Use *this in CChainState::InvalidateBlock

Summary:
This is a backport of core#21055 [10/16]
https://github.com/bitcoin/bitcoin/pull/21055/commits/1fb7b2c59505a6b9768789f6caad215a0a22ef16

Depends on D11214

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D11215