This update introduces four types of credential providers:
1. Environment variables
2. Configuration file
3. AWS STS
4. EC2 Metadata service
The first two providers should only be used for testing and local runs. **They must NEVER be used in production.**
The last two providers are intended for use on real EC2 instances:
- **AWS STS**: Preferred method for obtaining temporary credentials using IAM roles.
- **EC2 Metadata Service**: Should be used as a last resort.
Additionally, a simple credentials provider chain is created. It queries each provider sequentially until valid credentials are obtained. If all providers fail, it returns an empty result.
fixes: #21828Closesscylladb/scylladb#21830
* github.com:scylladb/scylladb:
docs: update the `object_storage.md` and `admin.rst`
aws creds: add STS and Instance Metadata service credentials providers
aws creds: add env. and file credentials providers
s3 creds: move credentials out of endpoint config