cluster-api-provider-aws: Throttling errors on DescribeLoadBalancers

/kind bug

What steps did you take and what happened: [A clear and concise description of what the bug is.] Reviewing CloudTrail logs for an account with around 20 provisioned clusters, frequent ThrottlingException events are found in for the DescribeLoadbalancers, which are then surrounded by AccessPointNotFoundException

What did you expect to happen: Not throttling at this level (20 clusters).

Anything else you would like to add: [Miscellaneous information that will assist in solving the issue.]

Environment:

• Cluster-api-provider-aws version: 0.4.x
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):