[Frontend] Use init_app_state and FrontendArgs in run_batch (#32967)

Signed-off-by: Pooya Davoodi <pooya.davoodi@parasail.io>
Co-authored-by: Cyrus Leung <tlleungac@connect.ust.hk>

tests/entrypoints/instrumentator/test_metrics.py

@@ -447,7 +447,7 @@ def test_metrics_exist_run_batch():
                 "--model",
                 "intfloat/multilingual-e5-small",
                 "--enable-metrics",
-                "--url",
+                "--host",
                 base_url,
                 "--port",
                 port,