Keep interrupts on when in battery saver mode

Battery saver was completely aborting the doze service, disabling
all interrupts. This is not ideal since it impacts the user journey,
especially when using face auth.

From now on the screen will still be off, but DozeService will be
retained, in order to receive sensor events.

Test: w/ battery saver: lift, tap, and observe aod being off
Test: w/ battery saver: receive notification, no HUN.
Test: w/o battery saver: lift, tap, and observe aod being on
Test: w/o battery saver: receive notification, HUN is received.
Fixes: 134157254
Change-Id: I9b713c78857c4e4c22d8d9bfff165b1b51dfd804