Add support for deleteKey for FileStore (#69953)
Summary:
torch_ucc uses `deleteKey`, and trying to run PyTorch tests with torch_ucc leads to failure about `deleteKey not implemented for FileStore`.
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69953
Reviewed By: ngimel
Differential Revision: D33458457
Pulled By: H-Huang
fbshipit-source-id: f46afd59f950722ae594d9aafb8843f14019e930
