Preload zip before waiting for surface flinger

This saves about 200 msec by preloading media zip file before waiting
for surface flinger becomes ready.

Android Auto results:
BootAnimation: BootAnimationPreloadTiming start time: 8261ms
BootAnimation: BootAnimationPreloadStopTiming start time: 8508ms

Bug: 62056504

Test: adb logcat -s BootAnimation
Change-Id: Iaedf774983a66c2838452c45a04b3a1f4c728f17