tests: Fix lock-order-inversion (potential deadlock) in DoS_tests.
Summary:
Reported by TSAN. Makes `src/test/test_bitcoin --run_test=DoS_tests` pass also when compiled with TreadSanitizer (`./configure --with-sanitizers=thread`).
Backport of core PR12882
https://github.com/bitcoin/bitcoin/pull/12882/files
Test Plan:
mkdir build && cd build
../configure --with-sanitizers=thread
make
export TSAN_OPTIONS="suppressions=${PWD}/../test/sanitizer_suppressions/tsan"
./src/test/test_bitcoin -t denialofservice_testsReviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D3606