Wait until end of BootAnimation to free looping textures

glDeleteTextures causes a noticeable framerate hitch when switching to
the outro.  By the time looping is finished, the system has finished
booting, so freeing the textures immediately is less beneficial.

Bug: 29878551
Bug: 30040263
Change-Id: I5a404a6e18cd2cf64d6c94343f82fa5db8dfbab3