fix(tests): remove the test breaking db isolation

This particular test breaks the DB isolation when running in parallel
with other tests. It's also not strictly needed given the behaviour is
in fact tested in other tests.

Author: Derik Evangelista

spec/unit/actions/service_credential_binding_create_spec.rb

@@ -51,20 +51,6 @@ module V3
             )
           end
 
-          it 'only creates one binding when creating bindings in parallel' do
-            errors = []
-            threads = 3.times.map do |i|
-              Thread.new do
-                action.precursor(service_instance, app: app, name: "binding-#{i}")
-              rescue => e
-                errors << e
-              end
-            end
-            threads.each(&:join)
-            expect(errors).to have(2).items
-            expect(errors.map(&:message).uniq).to contain_exactly('The app is already bound to the service instance')
-          end
-
           it 'raises an error when a the app and the instance are in different spaces' do
             another_space = Space.make
             another_app = AppModel.make(space: another_space)