[BugFix] Fix incorrect metrics shutdown error log message (#18992)

Signed-off-by: Nick Hill <nhill@redhat.com>

vllm/v1/metrics/prometheus.py

@@ -69,9 +69,13 @@ def unregister_vllm_metrics():
 
 def shutdown_prometheus():
     """Shutdown prometheus metrics."""
+
+    path = _prometheus_multiproc_dir
+    if path is None:
+        return
     try:
         pid = os.getpid()
-        multiprocess.mark_process_dead(pid)
+        multiprocess.mark_process_dead(pid, path)
         logger.debug("Marked Prometheus metrics for process %d as dead", pid)
     except Exception as e:
         logger.error("Error during metrics cleanup: %s", str(e))