Add RSS high-water mark in kilobytes

The new field will be used to reduce the upload size of RSS HWM metric.
Single int32 instead of int64.

Keep both fields populated on device for backwards compatibility.

Bug: 139269772
Test: atest MemoryStatUtilTest
Change-Id: Iea850a0baceabe07586147955fcfd11c46f8ac30
4 files changed