KCL consumer on kubernetes does not pick up IAM role via serviceAccount.

Deploying KCL consumer via kubernetes on aws EKS service does not pick up IAM role from serviceAccount with AWSCredentialsProvider = `DefaultAWSCredentialsProviderChain`, instead it uses node level role.

Following environment variables are present in the service, however it still doesn't seem to pick it up. However it works when I provide `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY`.

```
AWS_DEFAULT_REGION=
AWS_REGION=
AWS_ROLE_ARN=
AWS_WEB_IDENTITY_TOKEN_FILE=
```

Start by reproducing the KCL consumer on AWS EKS with a Kubernetes service account and the listed environment variables, then inspect how DefaultAWSCredentialsProviderChain selects credentials. Done means the consumer uses the service-account IAM role rather than the node-level role without explicit access keys.

Written by the indexing model from the issue text.