v3: Make service usage events spec less flaky

These tests would occasionally fail in CI when they ran in a certain
order. Tests were adding events to the database that other tests weren't
expecting to be there. Now, we make sure to clean up after the
newly-added test.

Similar to b15d26c

Authored-by: Reid Mitchell <rmitchell@pivotal.io>

Author: reidmit

spec/request/service_usage_events_spec.rb

@@ -165,6 +165,10 @@
       h.freeze
     end
 
+    after 'clean-up to avoid test pollution' do
+      VCAP::CloudController::ServiceUsageEvent.all.first.delete
+    end
+
     it_behaves_like 'permissions for single object endpoint', ALL_PERMISSIONS do
       let(:after_request_check) do
         lambda do