Launch help with system default theme

Fixes: 150651499
Test: Settings -> Battery -> click up right corner question icon, a
      help activity with system light/dark theme will be displayed
Change-Id: I58bfa6eee8af055d7aacb214b14cb50354a53853
(cherry picked from commit ef6766dd)
Merged-In: I58bfa6eee8af055d7aacb214b14cb50354a53853