PM#goToSleep and PM#wakeUp only affects default display group

This CL changes the behavior of PM#goToSleep to instead turn off the
power for the default display group. PM#wakeUp turns on the default
display group.

If all display groups are turned off, the device will go to sleep. If
any display group is on, the device will remain interactive.

This results in no behavior change if there is a single display group.
However if there are multiple display groups then it will be possible to
interact with ones that are on while others are off.

Bug: 138328918
Bug: 170935083
Bug: 175919649
Test: atest PowerManagerServiceTest
Change-Id: I8b475c38886eda3e43d6e8da7e68102a25da1584