UX: Show parent category name for category hashtags (#31188)

This commit changes the display of category hashtag
autocomplete to show the parent category name in this
format:

* Parent Name > Child Name

This helps further distinguish categories in the autocomplete
where there may be multiple different parent categories with
the same name child category, e.g. if every category has an
Announcements subcategory.

app/services/category_hashtag_data_source.rb

@@ -18,7 +18,14 @@ class CategoryHashtagDataSource
 
   def self.category_to_hashtag_item(category)
     HashtagAutocompleteService::HashtagItem.new.tap do |item|
-      item.text = category.name
+      item.text =
+        (
+          if category.parent_category
+            "#{category.parent_category.name} > #{category.name}"
+          else
+            category.name
+          end
+        )
       item.slug = category.slug
       item.description = category.description_text
       item.icon = icon