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.

Bug: 22207911
Change-Id: I0481f93d08f49c0de07c46550d0a113074f30765