tags: exclude deprecated tags from related tags list.

Don't show deprecated tags in the related tags or translated tags lists
when editing a post. It doesn't make sense to recommended adding tags
that can't be added to the post.

app/logical/related_tag_calculator.rb

@@ -59,7 +59,7 @@ module RelatedTagCalculator
 
     tags = Tag.from(tag_counts).joins("JOIN tags ON tags.name = tag")
     tags = tags.select("tags.*, overlap_count")
-    tags = tags.where("tags.post_count > 0")
+    tags = tags.nonempty.undeprecated
     tags = tags.where(category: category) if category.present?
     tags = tags.order("overlap_count DESC, tags.post_count DESC, tags.name")
     tags

app/logical/source/extractor.rb

@@ -227,7 +227,7 @@ module Source
 
     def translated_tags
       translated_tags = normalized_tags.flat_map(&method(:translate_tag)).uniq.sort
-      translated_tags.reject(&:artist?)
+      translated_tags.reject(&:artist?).reject(&:is_deprecated?)
     end
 
     # Given a tag from the source site, should return an array of corresponding Danbooru tags.