#18450 Remove persistence of Platform from process cache
Issue created by stuhood
The platform is currently persisted as a value in the process cache:
pants/src/rust/engine/process_execution/src/cache.rs
Lines 25 to 30 in </pantsbuild/pants/commit/f5710a2856d73d2c68c06298d87da11b49c5a8bb|f5710a2>
...but we have since moved to encoding the platform and environment in the cache key instead, meaning that we never need to retrieve it from the cache value.
We should remove this persistence, and simplify the naming of