Support multi-user privacy for battery usage chart

When there are multiple accounts in the devices, the battery usage list
is shared in the current design. We will aggregate other users usage
data into a single item to support multi-user privacy requirements

Screenshot: https://screenshot.googleplex.com/AkFTUtNvnoxcuGR

Bug: 202119550
Test: make RunSettingsRoboTests
Change-Id: I6cb55f0d50a4caca83212a0a54410530a032c089