* Add omitempty for DisableCompression and DisableKeepAlive fields in ScrapeConfig
* Add omitempty annotation to all the default/optional values
* Fix annotations after review
* Add improvements to ec2 discovery
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/771
role_arn support with aws sts
instance iam_role support
refreshing temporary tokens
* Apply suggestions from code review
Co-authored-by: Roman Khavronenko <hagen1778@gmail.com>
* changed implementation, removed tests, clean up code
* moved endpoint builder into getEC2APIResponse
Co-authored-by: Roman Khavronenko <hagen1778@gmail.com>