add retries to network operations (curl, conda install, git clone) (#30479)
Summary:
Addresses some of the top network-related flakiness occurrences.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30479
Differential Revision: D18736386
Pulled By: kostmo
fbshipit-source-id: 9eb5dca0cd0281894a0b304fbaf59a0341d3ff58
