Convert format strings using %u for bools to use %d instead

Summary: Tackling a low-priority ticket to start getting familiar with the code base: https://reviews.bitcoinabc.org/T90

Test Plan: Does this change need test changes? It seems minor enough to not bother, I think...

Reviewers: CCulianu, freetrader, O1 Bitcoin ABC, #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D605