Remove Security's access to the crematorium on RP

[AgrippaHera]

i don't like this; as a regular piano stealer i've personally witnessed that having a chaplain is a gamble unless it's highpop, where it is instead one of the most abscond-y jobs aboard. i can imagine sec will just use the port a brig & a grinder instead.

Having played a couple of rounds with the testmerge, I can attest to this happening. I've seen at least 3 separate changelings get grinded. Nobody even made a fuss about asking for the crematorium, because as I've previously mentioned, with particularly nasty changelings in busy rounds, you simply do not have the luxury to wait on a Chaplain, AI, HoP or Captain to deem it necessary to stop their RP and open the crematorium before the changeling inevitably starts rampaging again.

I don't necessarily see this as a negative. Before this change, the crematorium is really just a "changeling kill room" and it felt a bit odd. I'd rather have the room be used less as a ling-kill-room and more of a "The chaplain (or an antag with access) wanted to cremate a body" room. Maybe even give a crematorium to medbay...