Need to be able to specify session duration properly

[ngamber]

Problem

We noticed while using the opensearch plugin that when STS credentials are created using similar logic as this plugin, a session duration isn't specified, and so despite a much longer maximum session duration on the role itself, they default to 1 hour, which overwhelms the IAM role assumption role throttling built into AWS ES when using a large number of assume role calls on a domain.
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Steps to replicate

fluent/fluent-plugin-opensearch#68
Same thing would be present for any config using assume_role_arn in their stanza.

Expected Behavior or What you need to ask

We would like to have the option to specify and pass on duration_seconds to the STS credential provider here:

https://github.com/atomita/fluent-plugin-aws-elasticsearch-service/blob/master/lib/fluent/plugin/out_aws-elasticsearch-service.rb#L99

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Using Fluentd and ES plugin versions

Fluentd v1.14.4
fluent-plugin-aws-elasticsearch-service 2.4.1