Remove direct bitcoin calls from qt/bantablemodel.cpp

Summary:
Partial backport of Core PR 10244
https://github.com/bitcoin/bitcoin/pull/10244/commits/3034a462a5d30144cf0ec801d07f0c8c36d560f3
Progress towards T417
Depends on D2821

Test Plan:
make check
ninja
bitcoin-qt # sanity checking

Reviewers: deadalnix, Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D2822