iconGrid: Don't use clones for pulse animation

iconGrid: Don't use clones for pulse animation

The spring animation has to use clones to escape any clip set on the
parent, as it mainly occurs outside the parent. The same does not apply
to the pulse animation, which is very much in place - in fact, if the
parent is clipped (for instance a scrolled app folder), not having the
clip applied to the animated icons is indeed wrong.
Just animate the original grid actors instead, which gives the expected
result.

https://bugzilla.gnome.org/show_bug.cgi?id=736885