UX: Use localized time format in embedded comments (#28014)

Previously, the time format for embedded comments was hardcoded. This
commit changes it to the time format defined in I18n.

Related meta topic: https://meta.discourse.org/t/embed-dates-are-not-localized/27997/

app/helpers/embed_helper.rb

@@ -8,9 +8,9 @@ module EmbedHelper
       distance_of_time_in_words(dt, current)
     else
       if dt.year == current.year
-        dt.strftime("%e %b")
+        dt.strftime I18n.t("datetime_formats.formats.short_no_year")
       else
-        dt.strftime("%b '%y")
+        dt.strftime I18n.t("datetime_formats.formats.no_day")
       end
     end
   end