Add missing thread safety lock assertions in validation.{h|cpp}

Summary:
Co-authored-by: Shashwat <svangani239@gmail.com>

This is a backport of core#24177

Some of this work was already done in D4581.
Also add the lock annotation for CoinsDB which was missed in D7582

Test Plan:
With DEBUG and TSAN:

ninja all check check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12915