Change port range of dark storage

There is an issue where dark storage would try to use the same port as
ensemble evaluator. Switching the port range for dark storage should
fix this problem until we can fix the bug.

src/ert/services/_storage_main.py

@@ -106,7 +106,9 @@ def run_server(
         config_args.update(reload=True, reload_dirs=[os.path.dirname(ert_shared_path)])
         os.environ["ERT_STORAGE_DEBUG"] = "1"
 
-    sock = find_available_socket(custom_host=args.host)
+    sock = find_available_socket(
+        custom_host=args.host, custom_range=range(51850, 51870)
+    )
     connection_info = _create_connection_info(sock, authtoken)
 
     # Appropriated from uvicorn.main:run