[Feature] Support service account to use AWS IAM role

### Search before asking

- [x] I had searched in the [issues](https://github.com/apache/doris-operator/issues?q=is%3Aissue) and found no similar issues.

### Description

It would be great to support service account to use AWS IAM role. Thanks!

Seems today Doris does not support:
https://apachedoriscommunity.slack.com/archives/C02T886T5AR/p1741722243840209


### Use case

No need to set `s3.access_key` and `s3.secret_key` when query.

```
SELECT * FROM S3 (
"URI" = "s3://my-bucket/my.parquet",
"format" = "parquet",
"s3.endpoint" = "https://s3.us-west-2.amazonaws.com",
"s3.region" = "us-west-2",
"s3.access_key" = "xxx",
"s3.secret_key" = "xxx"
);
```

### Related issues

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)