Remove isolated useless assignments

These variables can be considered a block, and so removing them doesn't
make the test much harder to undestand.

Sometimes these variables formed the setup, sometimes they formed an
isolated part of the setup, and sometimes they were the part of the test
that made the test different from other tests.

spec/controllers/admin/api/stats_controller_spec.rb

@@ -64,9 +64,9 @@ describe Admin::Api::StatsController do
         time_1 = Time.zone.local(2017, 04, 01)
         time_2 = Time.zone.local(2017, 04, 02)
 
-        budget_investment1 = create(:budget_investment, created_at: time_1)
-        budget_investment2 = create(:budget_investment, created_at: time_2)
-        budget_investment3 = create(:budget_investment, created_at: time_2)
+        create(:budget_investment, created_at: time_1)
+        create(:budget_investment, created_at: time_2)
+        create(:budget_investment, created_at: time_2)
 
         sign_in user
         get :show, params: { budget_investments: true }