Add timeout failure comment in test; keep intentional TEST SUCEEDED convention

The 'TEST SUCEEDED' misspelling is an intentional convention in the pydevd
test framework (debugger_unittest.py checks stdout for this exact string).
Revert the resource file to preserve the convention while still adding the
explanatory comment requested in the test method.

Co-authored-by: rchiodo <19672699+rchiodo@users.noreply.github.com>

Author: Copilot

src/debugpy/_vendored/pydevd/tests_python/test_debugger_json.py

@@ -839,6 +839,9 @@ def test_case_json_continue_all_threads(case_setup_dap):
         # Send ContinueRequest with the specific thread's id (no singleThread=True).
         # Per the DAP spec this must resume ALL threads, not just the specified one.
         # The response must have allThreadsContinued=True.
+        # NOTE: If the fix regresses, the secondary thread stays blocked on
+        # stop_event.wait() and the debuggee hangs on t.join(), causing a test
+        # timeout rather than an explicit assertion failure.
         json_facade.write_continue(thread_id=json_hit.thread_id)
 
         writer.finished_ok = True