Merge bitcoin/bitcoin#30952: test: Use shell builtins in run_command test case

7bd3ee6 test: Use shell builtins in run_command test case (Ava Chow)

Pull request description:

  Uses the [suggested command](bitcoin/bitcoin#30938 (comment))

  Fixes #30938

ACKs for top commit:
  maflcko:
    review ACK 7bd3ee6
  hebasto:
    ACK 7bd3ee6.

Tree-SHA512: 683b15cafaf0103eeadf872ea6ce9a7d884b2605d3dcf4e66b0173cdb149c24965e7c5fa62aaddf2ac55df3f449aeb787176992c96cfee5d0b86621259e1dfe9

Author: fanquake

src/test/system_tests.cpp

@@ -47,7 +47,7 @@ BOOST_AUTO_TEST_CASE(run_command)
     }
     {
         // Return non-zero exit code, with error message for stderr
-        const std::string command{"python3 -c 'import sys; print(\"err\", file=sys.stderr); sys.exit(2)'"};
+        const std::string command{"sh -c 'echo err 1>&2 && false'"};
         const std::string expected{"err"};
         BOOST_CHECK_EXCEPTION(RunCommandParseJSON(command), std::runtime_error, [&](const std::runtime_error& e) {
             const std::string what(e.what());