[CPU] Fix arithmetic overflow and legacy TODO in Det operator (#27070)
### Description
This PR fixes the legacy `TODO: fix the warnings` in the `Det` operator.
The arithmetic overflow warning (C26451) is addressed by using `int64_t`
for tensor dimension and batch size calculations, ensuring safe pointer
arithmetic.
### Motivation and Context
- Removes unused warning suppression pragma.
- Prevents potential overflow when handling large batches of matrices.