Using the `_html` suffix automatically marks texts as HTML safe, so
doing so on sanitized texts is redundant.
Note flash texts are not sanitized the moment they are generated, but
are sanitized when displayed in the view.
Sometimes we're interpolating a link inside a translation, and marking
the whole translations as HTML safe.
However, some translations added by admins to the database or through
crowdin are not entirely under our control.
Although AFAIK crowdin checks for potential cross-site scripting
attacks, it's a good practice to sanitize parts of a string potentially
out of our control before marking the string as HTML safe.
