Deletes CCACHE_DISABLE and SCCACHE_DISABLE from nccl.cmake (#84007)
Looking through the code and online, it does not look like these variables actually change anything. Regardless, this change was instituted to fix https://github.com/pytorch/pytorch/issues/13362, but we are again running into similar issues even with the workaround: see https://github.com/pytorch/pytorch/issues/83790.
Thus, since
1. this change isn't preventing flakiness
2. these variables do not seem used anywhere in pytorch/pytorch nor mozilla/sccache
we should remove this confusion.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84007
Approved by: https://github.com/huydhn, https://github.com/malfet, https://github.com/ZainRizvi
