Revert to previous tag_validator behavior

This paritally reverts commit 9710063fdc
and reverts commit 7ddae61414

See thread: https://git.pleroma.social/pleroma/pleroma/-/merge_requests/4358#note_112761

test/pleroma/web/activity_pub/transmogrifier/note_handling_test.exs

@@ -200,7 +200,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier.NoteHandlingTest do
       assert match?(
                %{
                  "href" => "http://mastodon.example.org/tags/moo",
-                 "name" => "moo",
+                 "name" => "#moo",
                  "type" => "Hashtag"
                },
                Enum.at(object.data["tag"], 1)