Fix initialization of USER_ROTATION setting.

Until now, def_user_rotation was effectively a dead default:
- added missing def_user_rotation -> USER_ROTATION first-run initialization
- corrected the setting type when upgrading database

Bug: 178000973
Test: set def_user_rotation to 1 in default.xml and flash Pixel 3a
Change-Id: If2aa9665a0167f696f6b16a16be48ac473271631