Fix #6204: Use content warning for page title when present (#6231)

app/views/stream_entries/show.html.haml

 - content_for :page_title do
-  = t('statuses.title', name: display_name(@account), quote: truncate(@stream_entry.activity.text, length: 50, omission: '…'))
+  = t('statuses.title', name: display_name(@account), quote: truncate(@stream_entry.activity.spoiler_text.presence || @stream_entry.activity.text, length: 50, omission: '…'))
 
 - content_for :header_tags do
   - if @account.user&.setting_noindex