Add symlink resolution in benchmark timer interface (#82734)
### Description
The `sys.executable` string does not take into account if the file is a symlink or not. This lead to a false negative during checking if the two python interpreters were the same, while using an interpreter that was symlinked to another one.
Finding the realpath fixes the problem.
### Testing
Tested manually.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82734
Approved by: https://github.com/ngimel
Author
Mateusz Sypniewski
