[router] Add gRPC E2E test suite (#11790)

sgl-router/py_test/e2e_grpc/pytest.ini

@@ -0,0 +1,13 @@
+[pytest]
+# Show print statements and logs
+log_cli = true
+log_cli_level = INFO
+log_cli_format = %(asctime)s [%(levelname)8s] %(message)s
+log_cli_date_format = %Y-%m-%d %H:%M:%S
+
+# Show stdout/stderr
+addopts = -v -s --tb=short
+
+# Capture settings
+# -s means don't capture stdout (show print statements)
+# --tb=short means short traceback format