don't destructure Ember.testing

Module destructures are evaluated at build time, but this value is
changed dynamically at runtime. Avoiding the destructure is the only way
to work given this behavior. See these issues:

mainmatter/ember-simple-auth#1476
emberjs/ember-test-helpers#227

addon/services/apollo.js

@@ -17,10 +17,6 @@ import QueryManager from 'ember-apollo-client/apollo/query-manager';
 import copyWithExtras from 'ember-apollo-client/utils/copy-with-extras';
 import { registerWaiter } from '@ember/test';
 
-const {
-  testing,
-} = Ember;
-
 function newDataFunc(observable, resultKey, resolve, mergedProps = {}) {
   let obj;
   mergedProps[apolloObservableKey] = observable;
@@ -70,7 +66,7 @@ export default Service.extend({
     let config = getOwner(this).resolveRegistration("config:environment");
     if (config && config.apollo) {
       return config.apollo;
-    } else if (testing) {
+    } else if (Ember.testing) {
       return defaultOptions;
     }
     throw new Error("no Apollo service options defined");
@@ -87,7 +83,7 @@ export default Service.extend({
     let client = new ApolloClient(this.get('clientOptions'));
     this.set('client', client);
 
-    if (testing) {
+    if (Ember.testing) {
       this._registerWaiter();
     }
   },