Fix Valuation Investment index heading filters

Why:

Heading filter where not being correctly displayed

How:

Increasing scenario to cover all possible combinations, and fixing the
heading_filters method of the Valuation Budget Investment Controller to
correctly:
  * Find how many investments the valuator can access
  * Count investments for each heading

app/controllers/valuation/budget_investments_controller.rb

@@ -73,7 +73,9 @@ class Valuation::BudgetInvestmentsController < Valuation::BaseController
     end
 
     def heading_filters
-      investments = @budget.investments.by_valuator(current_user.valuator.try(:id)).distinct
+      investments = @budget.investments.by_valuator(current_user.valuator.try(:id))
+                                       .visible_to_valuators.distinct
+
       investment_headings = Budget::Heading.where(id: investments.pluck(:heading_id).uniq)
                                            .order(name: :asc)