Fix Rich Media Previews for updated activities

The Rich Media Previews were not regenerated when a post was updated due to a cache invalidation issue. They are now cached by the activity id so they can be evicted with the other activity cache objects in the :scrubber_cache.

lib/pleroma/html.ex

@@ -6,8 +6,6 @@ defmodule Pleroma.HTML do
   # Scrubbers are compiled on boot so they can be configured in OTP releases
   #  @on_load :compile_scrubbers
 
-  @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
-
   def compile_scrubbers do
     dir = Path.join(:code.priv_dir(:pleroma), "scrubbers")
 
@@ -67,27 +65,20 @@ defmodule Pleroma.HTML do
     end
   end
 
-  def extract_first_external_url_from_object(%{data: %{"content" => content}} = object)
+  @spec extract_first_external_url_from_object(Pleroma.Object.t()) ::
+          {:ok, String.t()} | {:error, :no_content}
+  def extract_first_external_url_from_object(%{data: %{"content" => content}})
       when is_binary(content) do
-    unless object.data["fake"] do
-      key = "URL|#{object.id}"
+    url =
+      content
+      |> Floki.parse_fragment!()
+      |> Floki.find("a:not(.mention,.hashtag,.attachment,[rel~=\"tag\"])")
+      |> Enum.take(1)
+      |> Floki.attribute("href")
+      |> Enum.at(0)
 
-      @cachex.fetch!(:scrubber_cache, key, fn _key ->
-        {:commit, {:ok, extract_first_external_url(content)}}
-      end)
-    else
-      {:ok, extract_first_external_url(content)}
-    end
+    {:ok, url}
   end
 
   def extract_first_external_url_from_object(_), do: {:error, :no_content}
-
-  def extract_first_external_url(content) do
-    content
-    |> Floki.parse_fragment!()
-    |> Floki.find("a:not(.mention,.hashtag,.attachment,[rel~=\"tag\"])")
-    |> Enum.take(1)
-    |> Floki.attribute("href")
-    |> Enum.at(0)
-  end
 end