activitypub: mrf: tag policy: refactor the filtering hook a bit

lib/pleroma/web/activity_pub/mrf/tag_policy.ex

@@ -87,21 +87,7 @@ defp process_tag(
 
   defp process_tag(_, message), do: {:ok, message}
 
-  @impl true
+  def filter_message(actor, message) do
-  def filter(%{"object" => target_actor, "type" => "Follow"} = message) do
-    User.get_cached_by_ap_id(target_actor)
-    |> get_tags()
-    |> Enum.reduce({:ok, message}, fn
-      tag, {:ok, message} ->
-        process_tag(tag, message)
-
-      _, error ->
-        error
-    end)
-  end
-
-  @impl true
-  def filter(%{"actor" => actor, "type" => "Create"} = message) do
     User.get_cached_by_ap_id(actor)
     |> get_tags()
     |> Enum.reduce({:ok, message}, fn
@@ -113,6 +99,14 @@ def filter(%{"actor" => actor, "type" => "Create"} = message) do
     end)
   end
 
+  @impl true
+  def filter(%{"object" => target_actor, "type" => "Follow"} = message),
+    do: filter_message(target_actor, message)
+
+  @impl true
+  def filter(%{"actor" => actor, "type" => "Create"} = message),
+    do: filter_message(actor, message)
+
   @impl true
   def filter(message), do: {:ok, message}
 end