Remove BDB dummy databases
Summary:
This is a backport of core#19102 [2/3]
https://github.com/bitcoin/bitcoin/pull/19102/commits/da039d2a915097c23f2b46e063042409bdc3c4f4
Depends on D10048
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, majcosta
Reviewed By: #bitcoin_abc, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D10049