Fix errors in automated testing

Errors like below occurred.

1) Drupal\Tests\aws_cloud\Functional\Ec2\SnapshotTest::testSnapshot
Exception: Error: Class 'Aws\Ec2\Ec2Client' not found
Drupal\aws_cloud\Service\AwsEc2Service->getEc2Client()() (Line: 144)

I added a composer.json file, where add the dependency to package aws-sdk-php.

In addition, I remove useless files *.test

Because the destination parameter is used in test case, the following errors occurred.

1) Drupal\Tests\aws_cloud\Functional\Ec2\ElasticIpTest::testElasticIp
Exception: User error: Redirects to external URLs are not allowed by default, use \Drupal\Core\Routing\TrustedRedirectResponse for it.
Drupal\Core\EventSubscriber\RedirectResponseSubscriber->checkRedirectUrl()() (Line: 84)

I removed the destination parameter, and changed redirect URL of XXXDeleteForm as below.

OLD:

$form_state->setRedirectUrl($this->getCancelUrl());

NEW:

    $form_state->setRedirect('view.aws_elastic_ip.page_1', ['cloud_context' => $entity->cloud_context()]);

@yas

Please review the patch file 3013528_20181115_2.patch.