Remove gitlab_routing_helper.rb: upgrade_plan_path
What does this MR do and why?
Remove gitlab_routing_helper.rb: upgrade_plan_path
Removes ee/app/helpers/ee/gitlab_routing_helper.rb: upgrade_plan_path
and its specs because it is not used anywhere. Solves a fraction of #420057
Changelog: removed EE: true
How to set up and validate locally
- Ensure pipelines pass