for #31321
# Details
Small updates from [community
PR](https://github.com/fleetdm/fleet/pull/31134):
* Updated config vars to match
[docs](https://github.com/fleetdm/fleet/blob/docs-v4.75.0/docs/Configuration/fleet-server-configuration.md#server_private_key_region)
* Added support for specifying region in config (already documented)
* Removed parsing of ARN for region
* Made retry backoff intervals a bit longer
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
- [X] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
(already added in the community PR
[here](https://github.com/fleetdm/fleet/blob/sgress454/updates-for-private-key-in-aws-sm/changes/private-key-secrets-manager#L0-L1)
## Testing
- [X] Added/updated automated tests
- [X] QA'd all new/changed functionality manually
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- New Features
- Added support for specifying the AWS region for server private key
retrieval from AWS Secrets Manager via server.private_key_region.
- Chores
- Renamed configuration keys:
- server.private_key_secret_arn → server.private_key_arn
- server.private_key_secret_sts_assume_role_arn →
server.private_key_sts_assume_role_arn
- server.private_key_secret_sts_external_id →
server.private_key_sts_external_id
- Update your configuration to use the new keys.
- Adjusted retry backoff for Secrets Manager retrieval to improve
resilience.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
