Ensure root access is disabled for AWS SageMaker Notebook instances

AWS SageMaker Notebook instances have root access enabled which may cause unauthorized access.

In AWS Console -

1. Sign in to the AWS Console and go to the Sagemaker dashboard.
2. Under Notebook on the navigation bar, select Notebook instances.
3. Select the Notebook Instance you wish.
4. Click Stop to stop the instance.
5. When the stop process has completed, click Edit.
6. Under Permissions and encryption, select Disable - Don't give users root access to the notebook.
7. Select Update Notebook Instance.
8. Start the Instance.

In Terraform -

1. In the aws_sagemaker_notebook_instance resource, set the 'root_access' attribute to 'Disabled'.

References:
https://docs.aws.amazon.com/sagemaker/latest/dg/nbi-root-access.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/sagemaker_notebook_instance#root_access