Fix name collision in crypto_tests

Summary:
Avoid name collision between src/test/crypto_tests.cpp and
src/wallet/test/crypto_tests.cpp. This collision would prevent from
running test_bitcoin --run_test=crypto_tests.

This fix is extracted from core PR12719 and PR12895.

Test Plan:

make check
ninja check

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2519