Remove emulator specific code around STAY_ON_WHILE_PLUGGED_IN

emulator has its own provisioning app, we will set this
value there.

Bug: 314313875
Test: boot emulator, check the STAY_ON_WHILE_PLUGGED_IN value
Change-Id: I653074dd3954e8dc5dbbd4c7d136744988f32416
Signed-off-by: Roman Kiryanov <rkir@google.com>