Enable EXPENSIVE_RENDERING power hint

GPU takes long time (>8ms) when app launch animation and some pip case.
When doing animation, GPU needs to handle some heavy tasks like color
conversion, app rounded corner. Enable the expensive rendering hint to
raise the gpu frequency to avoid frame drop due to long gpu completion.

Bug: 179007786
Test: 1. Open Chrome/Chrome with pip from homescreen
         Swipe vertically to go back to home screen
         Measure the gpu completion time and "FrameMissed" count from systrace result
      2. 4K60fps HDR Video playback and measure the DoU Power impact
Change-Id: I37f92018e5fd5a925189431db39409f11079b778