Remove unused methods from `RenderPartialWithRecordIdentificationController`

These methods no longer used since a3da293b.

actionview/test/activerecord/render_partial_with_record_identification_test.rb

@@ -17,21 +17,11 @@ def render_with_scope
     render partial: Reply.base
   end
 
-  def render_with_has_many_through_association
-    @developer = Developer.first
-    render partial: @developer.topics
-  end
-
   def render_with_has_one_association
     @company = Company.find(1)
     render partial: @company.mascot
   end
 
-  def render_with_belongs_to_association
-    @reply = Reply.find(1)
-    render partial: @reply.topic
-  end
-
   def render_with_record
     @developer = Developer.first
     render partial: @developer