Display only current budget to Managers printing investments

In the specs, some investment were missing a heading_id, thus creating
another unexpected budget

By explicitly setting the heading_id we can control better which
budgets are created in each test

app/controllers/management/budgets_controller.rb

@@ -19,7 +19,7 @@ class Management::BudgetsController < Management::BaseController
   end
 
   def print_investments
-    @budgets = Budget.current.order(created_at: :desc).page(params[:page])
+    @budget = Budget.current
   end
 
   private