Use the default AWS Credentials Provider

Per https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/credentials.html, when no credentials provider is configured, the SDK will iterate through several providers to to find the appropriate credentials.

If this line, https://github.com/debezium/debezium/blob/5b757372d82f79d314f0392b516cf63245fc72a9/debezium-server/debezium-server-kinesis/src/main/java/io/debezium/server/kinesis/KinesisChangeConsumer.java#L82, is removed, then the SDK will use this user-friendly, and flexible, method to fetch credentials, vs requiring users to create a config file. As it is, this does not work with IRSA (IAM Roles for Service Accounts), even with a custom client in the classpath, and so we are forced to create users with credentials vs using role assumption.