perfboot.py: check 2 more event logs by default

'sf_stop_bootanim' is useful for tracking the time wasted by
showing the 'outro' part of the boot animation.

'wm_boot_animation_done' is also useful for tracking user
perceived boot time.

(cherry-pick of cbcf2778)

Bug: 22207911
Change-Id: I3549338a2161fa29675993c239f57809270797f8