Fix warning in kineto_shim.h (#85653)
Fixes:
```
In file included from /dev/shm/rbarnes/tempfs/pytorch/torch/csrc/profiler/kineto_shim.cpp:1:
/dev/shm/rbarnes/tempfs/pytorch/torch/csrc/profiler/kineto_shim.h:111:8: warning: private field 'saved_' is not used [-Wunused-private-field]
bool saved_ = false; // Kineto's save is destructive
^
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85653
Approved by: https://github.com/ezyang
