Use budget phase traits

We were already using them in many places, but not everywhere.

spec/features/budgets/ballots_spec.rb

@@ -3,7 +3,7 @@ require "rails_helper"
 describe "Ballots" do
 
   let!(:user)       { create(:user, :level_two) }
-  let!(:budget)     { create(:budget, phase: "balloting") }
+  let!(:budget)     { create(:budget, :balloting) }
   let!(:states)     { create(:budget_group, budget: budget, name: "States") }
   let!(:california) { create(:budget_heading, group: states, name: "California", price: 1000) }
   let!(:new_york)   { create(:budget_heading, group: states, name: "New York", price: 1000000) }

spec/features/budgets/votes_spec.rb

@@ -4,7 +4,7 @@ describe "Votes" do
 
   describe "Investments" do
     let(:manuela) { create(:user, verified_at: Time.current) }
-    let(:budget)  { create(:budget, phase: "selecting") }
+    let(:budget)  { create(:budget, :selecting) }
     let(:group)   { create(:budget_group, budget: budget) }
     let(:heading) { create(:budget_heading, group: group) }