ci: Use SCCACHE_S3_KEY_PREFIX in CI builds (#82103)
Was noticing some concerning stats when fixing some macOS builds where we were experiencing a ton of cache misses. This makes it so that there is a separate cache for each particular workflow which should hopefully reduce the amount of cache misses we experience and speed up CI by a lot.
Relates to https://github.com/mozilla/sccache/pull/811
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82103
Approved by: https://github.com/kit1980
