test: use MiniWallet for feature_dbcrash.py

Summary:

This test can now be run even with the Bitcoin Core wallet disabled.

Backport of core#25087.

Test Plan:
With wallet disabled:

./test/functional/test_runner.py feature_dbcrash

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D16419