Adjust Battery Saver percentage slide size (sync from ag/13330588)

Screenshots:
     https://screenshot.googleplex.com/72qRevtZXA4PTcg.png
     https://screenshot.googleplex.com/3rJjDRehdsPL8AQ.png

Bug: 157532287
Bug: 202295741
Test: make SettingsGoogleRoboTests
Merged-In: Ia4453261c22919e325a971237efc79b4887362ec
Change-Id: I09fe6fe3de6da45959ee0babbd34202340ec661d