Try optimizing animate_targets system

[alice-i-cecile]

Will it faster if we keep the &AnimationTarget here instead of checking if entity has AnimationTarget at line 1114？I think it could help reduce the search scope.

Originally posted by @pyhinox in #15282 (comment)

[alice-i-cecile]

Try it, see if it's faster on many_foxes and report back!

[chescock]

I did not do that in only three minutes :). I had noticed the issue yesterday and was making a PR anyway when I saw this issue to attach it to.

[alice-i-cecile]

@phyinox I'd appreciate your review here if you have the time :)