[Dynamo] Remove deadcode: unwrapping script_if_tracing (#120444)
After the consolidated ```trace_rules.lookup```, we already unwrap at
https://github.com/pytorch/pytorch/blob/2240018c03744ee34ea14ad53481db934c37e384/torch/_dynamo/variables/builder.py#L712
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120444
Approved by: https://github.com/anijain2305
