fix(amplify-provider-awscloudformation): consolidate region list

This commit uses the region list exported from aws-regions.js in
aws-utils/aws-amplify.js instead of duplicating the list.

packages/amplify-provider-awscloudformation/src/aws-utils/aws-amplify.js

@@ -1,21 +1,7 @@
 const aws = require('aws-sdk');
 const proxyAgent = require('proxy-agent');
 const configurationManager = require('../configuration-manager');
-
-const amplifyServiceRegions = [
-  'us-east-1',
-  'us-east-2',
-  'us-west-2',
-  'eu-west-1',
-  'eu-west-2',
-  'eu-central-1',
-  'ap-northeast-1',
-  'ap-northeast-2',
-  'ap-south-1',
-  'ap-southeast-1',
-  'ap-southeast-2',
-  'ca-central-1',
-];
+const { regions: amplifyServiceRegions } = require('../aws-regions');
 
 async function getConfiguredAmplifyClient(context, options = {}) {
   let cred = {};