Remove libstatslog from libstatsmetadata

Instead of relying on the constants in libstatslog, hardcode them in
atoms_info to get rid of the dependency on libstatslog

New generated atoms_info.cpp:
https://paste.googleplex.com/5779947622760448

Bug: 150417465
Test: m libstatsmetadata
Change-Id: I954c963f1883f889053b63d308c648548de71e56