SageMaker Unified Studio: default_bucket returning incorrect bucket and default_bucket_prefix returning None from sagemaker_core python SDK

**Describe the bug**
default_bucket returning incorrect bucket and default_bucket_prefix returning None from sagemaker_core python SDK in SageMaker Unified Studio. This works fine in sagemaker python sdk.

As a temporary workaround, this commit has been merged: https://github.com/aws/amazon-sagemaker-examples/pull/4812/commits/ccdfae270d563f6c031bc70aed34eb02b1a863f7

**To reproduce**
In a JupyterLab notebook running in SageMaker Unified Studio

```
from sagemaker_core.helper.session_helper import get_execution_role, Session

sagemaker_session = Session()

s3_bucket_name = sagemaker_session.default_bucket()
default_bucket_prefix = sagemaker_session.default_bucket_prefix

print(f"Test s3_bucket_name: {s3_bucket_name}")
# Prints something like sagemaker-us-east-2-715841365766, when it should print something likeamazon-sagemaker-715841365766-us-east-2-018ae31e0f88

print(f"Test default_bucket_prefix: {default_bucket_prefix}")
# Prints None, when it should print a string
```

**Expected behavior**
In psuedocode above.

**Additional info**
This [commit](https://github.com/aws/amazon-sagemaker-examples/pull/4812/commits/ccdfae270d563f6c031bc70aed34eb02b1a863f7
) may be updated to pull default_bucket and default_bucket_prefix from sagemaker_core instead of sagemaker once this issue has been fixed.