Add 25% and 75% lines to improve the readability of the battery level as a short-term fix.

[Screenshot]
Before: https://screenshot.googleplex.com/5WDToTZsRcosbjC
After:  https://screenshot.googleplex.com/C4XJ4Mnigxa27gq

Bug: 260498797
Fix: 260498797
Test: Manual
Change-Id: I08c8ec3b2868c59d341ce34d93b6e010e3440cf5