Fix Transmogrifier tests

These tests relied on the removed Fetcher.fetch_object_from_id!/2 function injecting the error tuple into a log message with the exact words "Object containment failed."

We will keep this behavior by generating a similar log message, but perhaps this should do a better job of matching on the error tuple returned by Transmogrifier.handle_incoming/1

lib/pleroma/object/fetcher.ex

@@ -75,8 +75,9 @@ def fetch_object_from_id(id, options \\ []) do
       {:allowed_depth, false} ->
         {:error, "Max thread distance exceeded."}
 
-      {:containment, _} ->
-        {:error, "Object containment failed."}
+      {:containment, e} ->
+        Logger.info("Error while fetching #{id}: Object containment failed. #{inspect(e)}")
+        {:error, e}
 
       {:transmogrifier, {:error, {:reject, e}}} ->
         Logger.info("Rejected #{id} while fetching: #{inspect(e)}")