test: Add BerkeleyDatabase tsan suppression

Summary:
I noticed an occasional failure when running the wallet_multiwallet.py functional test using TSAN with clang-12.

This is a backport of core#19226

Test Plan:
With TSAN:

TSAN_OPTIONS=suppressions=/home/pierre/dev/bitcoin-abc/test/sanitizer_suppressions/tsan test/functional/test_runner.py wallet_multi*

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10544