Reduce size of procstats westworld atoms

Deprecate unwanted fields in procstats atom & reduce resolution of int64
numeric fields.

Once the deprecated fields are no longer populated, this change will
significantly reduce the size of the procstats westworld atoms,
meaning it will be easier to upload them.

Change-Id: I9cad36ef48faa06c9c48e1ecfac27a577e4be17d
Test: refactoring CL. Existing unit tests still pass.
BUG: 145203981