Rest API to create a table using "STS AssumeRole with a Permanent Access Key Pair (No OIDC)" failed with exception on "VAST Data"

### Describe the bug

I am receiving the following error when invoke create table using polaris RestAPI. I am using Sts in VAST (underlying S3 storage). I am using 1.5.0 release tag
{
"error": {
"message": "Failed to get subscoped credentials: A header you provided implies functionality that is not implemented. (Service: Sts, Status Code: 501, Request ID: 1eb1d101f4978f, Extended Request ID: 1eb1d101f4978f) (SDK Attempt Count: 1)",
"type": "UnprocessableEntityException",
"code": 422
}
}

### To Reproduce

1. Invoking the API https:///api/catalog/v1//namespaces//tables/ by enabling header "X-Iceberg-Access-Delegation"
2. Catalog information
{
"type": "INTERNAL",
"name": "scct_catalog_v3",
"properties": {
"s3.access-key-id": "xxxx",
"s3.secret-access-key": "xxx",
"default-base-location": "s3://purchase-order/warehouse-v2",
"s3.endpoint": "https://obj-centraldtq.storage.lowes.com:443"
},
"createTimestamp": 1784361133731,
"lastUpdateTimestamp": 1784361133731,
"entityVersion": 1,
"storageConfigInfo": {
"roleArn": "arn:vast:iam::xxx:role/control-tower-iamrole",
"externalId": "xxx",
"allowedKmsKeys": [],
"region": "us-east-1",
"endpoint": "https://xxx:443",
"stsEndpoint": "https://xxx",
"endpointInternal": "https://xxx:443",
"pathStyleAccess": true,
"kmsUnavailable": true,
"storageType": "S3",
"allowedLocations": [
"s3://purchase-order/warehouse-v2"
]
}
}

### Actual Behavior

_No response_

### Expected Behavior

_No response_

### Additional context

_No response_

### System information

OS: Linux
Objedt Storage: S3, VAST, us-east1

Start by reproducing the create-table request at the catalog REST endpoint with X-Iceberg-Access-Delegation enabled, using the 1.5.0 release and the supplied VAST STS configuration. Trace the failed subscoped-credentials operation and compare its STS request with VAST's supported behavior; done means the request succeeds or the incompatibility is clearly identified and covered by an appropriate regression check.

Written by the indexing model from the issue text.