[backport#15623] refactor: Expose UndoReadFromDisk in header

Summary:
https://github.com/bitcoin/bitcoin/pull/15623/commits/fa11c036e97f18d31cffaf7430fbe84fe44efbcc

Backport of Core PR15623

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D6304