Increase expiration of get merge requests API cache

MR: gitlab.com/gitlab-org/gitlab/-/merge_requests/68465

lib/api/merge_requests.rb

@@ -202,7 +202,7 @@ module API
         options[:project] = user_project
 
         if Feature.enabled?(:api_caching_merge_requests, user_project, type: :development, default_enabled: :yaml)
-          present_cached merge_requests, expires_in: 10.minutes, **options
+          present_cached merge_requests, expires_in: 12.hours, **options
         else
           present merge_requests, options
         end