searchable: replace find_ordered with in_order_of.

Rails 7 added an `in_order_of` method that does what our `find_ordered`
method did before.

app/logical/concerns/searchable.rb

@@ -592,7 +592,7 @@ module Searchable
     if params[:order] == "custom"
       parse_ids = PostQueryBuilder.new(nil).parse_range(params[:id], :integer)
       if parse_ids[0] == :in
-        return find_ordered(parse_ids[1])
+        return in_order_of(:id, parse_ids[1])
       end
     end
 
@@ -603,14 +603,6 @@ module Searchable
     order(id: :desc)
   end
 
-  def find_ordered(ids)
-    order_clause = []
-    ids.each do |id|
-      order_clause << sanitize_sql_array(["#{qualified_column_for(:id)} = ? DESC", id])
-    end
-    where(id: ids).order(Arel.sql(order_clause.join(', ')))
-  end
-
   private
 
   def qualified_column_for(attr)

app/logical/post_query_builder.rb

@@ -736,7 +736,7 @@ class PostQueryBuilder
     operator, ids = parse_range(id_metatags.first, :integer)
     return relation.none unless operator == :in
 
-    relation.find_ordered(ids)
+    relation.in_order_of(:id, ids)
   end
 
   # @raise [TagLimitError] if the number of tags exceeds the user's tag limit

app/models/post.rb

@@ -962,7 +962,7 @@ class Post < ApplicationRecord
         random_up(key) || random_down(key)
       end.compact.uniq
 
-      reorder(nil).find_ordered(posts.map(&:id))
+      reorder(nil).in_order_of(:id, posts.map(&:id))
     end
 
     def random_up(key)