I have that same model heatsink and I believe that it does not come with a temp sensor, My Macbook is model number 5’2 (mid 2009) and there is no cable attached to the heatsink at all. Although the motherboard has a connector for a temp sensor but does need one. The GPU and CPU are oriented differently then any of the pictures on this site for this particular model. I’m guessing the temp sensor is built in to the CPU and GPU as there is no cable for one.

I have the same model as you and was stopped by this discovery, what i would try to do is remove them with pliers anyway and just use some spare small screws in the holes and see if that works, but I think no harm would happen if you just leave them out since it’s just a plate being held on and no important components are being held in place exclusively by the black pins.