ci: Remove redundant RUN_UNIT_TESTS_SEQUENTIAL

.github/workflows/ci.yml

@@ -379,7 +379,7 @@ jobs:
       - name: Run unit tests
         # Can't use ctest here like other jobs as we don't have a CMake build tree.
         run: |
-          ./bin/test_bitcoin.exe -l test_suite
+          ./bin/test_bitcoin.exe -l test_suite  # Intentionally run sequentially here, to catch test case failures caused by dirty global state from prior test cases.
           ./src/secp256k1/bin/exhaustive_tests.exe
           ./src/secp256k1/bin/noverify_tests.exe
           ./src/secp256k1/bin/tests.exe