[cloud] Extend AWSRetry to also retry on `Throttling` exceptions (#22698)

We use ansible+cloudformation pretty heavily in our CI environments and occasionally bump into throttling issues.  By adding this error code to the retry system we should be able to achieve better stability.

lib/ansible/module_utils/ec2.py

@@ -85,7 +85,8 @@ class AWSRetry(CloudRetry):
         # https://github.com/boto/boto3/issues/876 (and linked PRs etc)
         retry_on = [
             'RequestLimitExceeded', 'Unavailable', 'ServiceUnavailable',
-            'InternalFailure', 'InternalError', 'TooManyRequestsException'
+            'InternalFailure', 'InternalError', 'TooManyRequestsException',
+            'Throttling'
         ]
 
         not_found = re.compile(r'^\w+.NotFound')