Move more non-AB code to separate files

non-AB has different lifetime and development cycles from AB. To avoid
accidentally breaking each other when making changes, put non-AB code in
its own files.

Test: local non-AB OTA generation
Bug: 296485685

Merged-In: I0736ecef343834c746464666a454a8bfcd4a20ea

Change-Id: I0736ecef343834c746464666a454a8bfcd4a20ea