Apply diff view cookie on compare

Closes #19573

CHANGELOG

@@ -37,6 +37,7 @@ v 8.10.0 (unreleased)
   - The Markdown reference parsers now re-use query results to prevent running the same queries multiple times !5020
   - Updated project header design
   - Issuable collapsed assignee tooltip is now the users name
+  - Fix compare view not changing code view rendering style
   - Exclude email check from the standard health check
   - Updated layout for Projects, Groups, Users on Admin area !4424
   - Fix changing issue state columns in milestone view

app/controllers/projects/compare_controller.rb

@@ -15,6 +15,7 @@ class Projects::CompareController < Projects::ApplicationController
   end
 
   def show
+    apply_diff_view_cookie!
   end
 
   def diff_for_path