Add input validation and resource management improvements

[aviruthen]

Issue #, if available:

Description of changes:

Adds additional input validation and resource management improvements to prevent accidental customer misuse.

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[aviruthen]

Codebuild for integration tests actually did succeed, it just took 3 hours and 7 minutes. Failure in PR check is due to security token expiring after 3 hours so GitHub action fails, but the actual run itself passed.

[aviruthen]

All checks have passed in the past as well as shown here: https://github.com/aws/sagemaker-python-sdk/actions/runs/20321321055/job/58445294129. No changes have been made since this point other than to update the target branch (master)