Silent rm error for sccache log file (#64388)
Summary:
Sample reporting from dr.ci
![image](https://user-images.githubusercontent.com/658840/131724645-75afa04f-7554-4674-8e7c-cf139c84d994.png)
The `rm` command is not actually running into problems, just need to silent the console output.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64388
Reviewed By: walterddr, malfet, seemethere
Differential Revision: D30704439
Pulled By: zhouzhuojie
fbshipit-source-id: ecd35531decf05b75cef30d08d46635f81112f67