federator: don't fetch the user for no reason

The return value is never used here; later stages which actually need it
fetch the user themselves and it doesn't matter wheter we wait for the
fech here or later (if needed at all).

Even more, this early fetch always fails if the user was already deleted
or never known to begin with, but we get something referencing it; e.g.
the very Delete action carrying out the user deletion.
This prevents processing of the Delete, but before that it will be
reattempted several times, each time attempring to fetch the
non-existing profile, wasting resources.

lib/pleroma/web/federator.ex

@@ -91,8 +91,7 @@ def perform(:incoming_ap_doc, params) do
 
     # NOTE: we use the actor ID to do the containment, this is fine because an
     # actor shouldn't be acting on objects outside their own AP server.
-    with {_, {:ok, _user}} <- {:actor, User.get_or_fetch_by_ap_id(actor)},
-         nil <- Activity.normalize(params["id"]),
+    with nil <- Activity.normalize(params["id"]),
          {_, :ok} <-
            {:correct_origin?, Containment.contain_origin_from_id(actor, params)},
          {:ok, activity} <- Transmogrifier.handle_incoming(params) do