Revert "Prevent callback overruns in InvalidateBlock and RewindBlockIndex"

Summary:
This reverts commit a9734a4e30ae12336bce10ef16cd6fd1198b3034.

Similar to D4950 but using git revert.

Test Plan:

ABC_BUILD_NAME=build-tsan ./contrib/teamcity/build-configurations.sh

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D4959