Fix power usage detail page is launched in wrong user

Two issues:
1. UID of settings app == system UID. But isSystemUid failed to recognize
Settings in secondary user is also a system uid.
2. For USER drain type, we should launch the detail page in current
   user.

Fix: 64506728
Test: make ROBOTEST_FILTER=AdvancedPowerUsageDetailTest -j40 RunSettingsRoboTests
Test: Switch to seconday user. Go to Settings->Battery, tap owner user
      battery entry, observe that detail page is shown.
Test: Stay long enough in Settings app, make sure no
      either Settings nor Android Framework battery entry.

Change-Id: I8d66ad55f18fcb3d9567b3bf753f737f5b98c609