Redfish integration tests: Discard stdout of Redfish mock servers

These mock servers produce a lot of stdout, causing buffering issues. Since we
anyway don't use it, we might as well discard it. Note that these buffering
issues did not cause any test failures (since calling the mock servers at least
once worked), but avoiding them is of course more correct.

Change-Id: I4720673d8d816ec726efa46579782b79eb0a6072

tests/integration_redfish/lib.py

@@ -80,7 +80,7 @@ def create_special_agent_rule(
 def run_mockup_server(*, dataset_path: Path, port: int) -> subprocess.Popen:
     return subprocess.Popen(
         ["python3", _MOCKUP_SERVER_FILE, "--port", f"{port}", "-D", dataset_path],
-        stdout=subprocess.PIPE,
+        stdout=subprocess.DEVNULL,
         stderr=subprocess.PIPE,
         text=True,
     )