Adding retries to AWS API calls

[epytka]

Proposed Changes

Since 3.8.18, RabbitMQ AWS peer discovery (https://www.rabbitmq.com/cluster-formation.html) mechanism no longer uses randomized delays to avoid the inherent race condition during initial cluster formation (https://www.rabbitmq.com/cluster-formation.html#initial-formation-race-condition). Instead it relies on an internal distributed locking mechanism available in modern Erlang releases (23.2 and newer).

Currently, AWS does not support SDK for Erlang; hence calling AWS service APIs are done with a simple implementation that wraps the httpc Erlang module. It constructs HTTP requests for AWS service queries and send to AWS service endpoints. Upon receiving responses, it parses response body for expected data. The existing implementation does not support any retry mechanism yet. As a good practice, AWS service clients should retry on transient network issues or service errors (5xx) received from AWS services.

That being said, a simple fix for this lock/unlock issue is to retry when transient network issues.

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