Put pluto test in one common file (#1934)

tests/datascience-notebook/test_pluto_datascience.py

@@ -0,0 +1,13 @@
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+import requests
+
+from tests.conftest import TrackedContainer
+from tests.pluto_check import check_pluto_proxy
+
+
+def test_pluto_proxy(
+    container: TrackedContainer, http_client: requests.Session
+) -> None:
+    """Pluto proxy starts Pluto correctly"""
+    check_pluto_proxy(container, http_client)