object: downgrade normalize warning to debug severity

lib/pleroma/object.ex

@@ -47,18 +47,22 @@ def normalize(%Activity{object: %Object{} = object}), do: object
   # Catch and log Object.normalize() calls where the Activity's child object is not
   # preloaded.
   def normalize(%Activity{data: %{"object" => %{"id" => ap_id}}}) do
-    Logger.info(
+    Logger.debug(
       "Object.normalize() called without preloaded object (#{ap_id}).  Consider preloading the object!"
     )
 
+    Logger.debug("Backtrace: #{inspect(Process.info(:erlang.self(), :current_stacktrace))}")
+
     normalize(ap_id)
   end
 
   def normalize(%Activity{data: %{"object" => ap_id}}) do
-    Logger.info(
+    Logger.debug(
       "Object.normalize() called without preloaded object (#{ap_id}).  Consider preloading the object!"
     )
 
+    Logger.debug("Backtrace: #{inspect(Process.info(:erlang.self(), :current_stacktrace))}")
+
     normalize(ap_id)
   end