use scrub_html_and_truncate instead of scrub_html for feed item title

Sometimes this truncated properly encoded HTML entities in the
wrong place.  The new flow calls scrub_html, removes emojis,
decodes entities (a second time), truncates, and then re-encodes.

Fixes #3045.

lib/pleroma/web/feed/feed_view.ex

@@ -83,9 +83,8 @@ defmodule Pleroma.Web.Feed.FeedView do
       end
 
     title
-    |> Pleroma.Web.Metadata.Utils.scrub_html()
-    |> Pleroma.Emoji.Formatter.demojify()
-    |> Formatter.truncate(opts[:max_length], opts[:omission])
+    |> Pleroma.Web.Metadata.Utils.scrub_html_and_truncate(opts[:max_length], opts[:omission])
+    |> HtmlEntities.encode()
   end
 
   def activity_description(data) do