Revert #6479, hide sensitive text/images from OpenGraph previews (#6818)

Display summary of attachments in description, and mark up content
warning if present, e.g.:

    Attached: 3 images · Content warning: Dota 2

When text is not supposed to be hidden, it looks more like:

    Attached: 3 images

    Here is the text of the toot

With #6817, multilinguagility should be assured...

app/views/accounts/show.html.haml

@@ -1,5 +1,5 @@
 - content_for :page_title do
-  = "#{display_name(@account)} (@#{@account.username})"
+  = "#{display_name(@account)} (@#{@account.local_username_and_domain})"
 
 - content_for :header_tags do
   %meta{ name: 'description', content: account_description(@account) }/