test: Remove spurious double lock tsan suppressions by bumping to clang-12

Summary:
This and D12118 should clear the TSAN issues on bullseye.

Backport of core#21669.

Test Plan:

./contrib/teamcity/build-configurations.py build-tsan

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D12119