[core] Don't clobber look string data for entities that dont have it

[WinterSolstice8]

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What does this pull request do?

tl;dr: we don't currently store model hitbox size and graph size for non player/mob/pet so we don't want to override what was memcpyed from look string/namevis/whatever

Steps to test these changes

!cs 705 in whitegate
before:

after: