Change `foo.should` syntax to `expect(foo).to` in specs

spec/controllers/autocomplete_controller_spec.rb

spec/features/notes_on_merge_requests_spec.rb

spec/lib/gitlab/ldap/access_spec.rb

spec/lib/gitlab/o_auth/auth_hash_spec.rb

spec/models/external_wiki_service_spec.rb

spec/models/project_services/irker_service_spec.rb

spec/requests/api/issues_spec.rb

spec/requests/api/merge_requests_spec.rb

spec/requests/api/milestones_spec.rb

spec/requests/api/projects_spec.rb

spec/services/destroy_group_service_spec.rb

spec/services/projects/destroy_service_spec.rb

spec/services/projects/transfer_service_spec.rb