Added changelog

Also removed redundant code

app/controllers/projects/protected_branches_controller.rb

 class Projects::ProtectedBranchesController < Projects::ApplicationController
-  include RepositoryHelper
   # Authorize
   before_action :require_non_empty_project
   before_action :authorize_admin_project!

changelogs/unreleased-ee/26732-combine-deploy-keys-and-push-rules-and-mirror-repository-and-protect-branches-settings-pages-ee.yml

+---
+title: Combined deploy keys and push rules settings options into a single one called
+  Repository
+merge_request:
+author: