[SfStats] Temporarily enable timestats by default.

Dogfood devices right now don't have telemetry enabled while we move
onto statsd, so this code is not exercised at all in dogfood.

Bug: 136597024
Bug: 140266250
Test: adb shell dumpsys SurfaceFlinger --timestats -dump
Change-Id: Ia11b980107efc8a8788aa3720ebd735f63a5fb8a