OwnershipUtils: check for SILInstructionKind instead of SILNodeKind
OwnershipUtils: check for SILInstructionKind instead of SILNodeKind

This resolves a FIXME.
Also, use `getDefiningInstruction()` instead of `getRepresentativeSILNodeInObject()`

NFC

atrick/swift,hooman/swift,xwu/swift,gregomni/swift,hooman/swift,JGiola/swift,rudkx/swift,atrick/swift,roambotics/swift,hooman/swift,xwu/swift,tkremenek/swift,hooman/swift,roambotics/swift,parkera/swift,glessard/swift,hooman/swift,hooman/swift,gregomni/swift,ahoppen/swift,xwu/swift,rudkx/swift,rudkx/swift,gregomni/swift,JGiola/swift,tkremenek/swift,parkera/swift,atrick/swift,atrick/swift,JGiola/swift,apple/swift,glessard/swift,tkremenek/swift,tkremenek/swift,rudkx/swift,parkera/swift,parkera/swift,ahoppen/swift,gregomni/swift,atrick/swift,roambotics/swift,xwu/swift,apple/swift,benlangmuir/swift,roambotics/swift,roambotics/swift,xwu/swift,JGiola/swift,ahoppen/swift,parkera/swift,benlangmuir/swift,benlangmuir/swift,glessard/swift,roambotics/swift,parkera/swift,glessard/swift,glessard/swift,ahoppen/swift,benlangmuir/swift,tkremenek/swift,atrick/swift,apple/swift,rudkx/swift,benlangmuir/swift,tkremenek/swift,glessard/swift,JGiola/swift,JGiola/swift,xwu/swift,parkera/swift,hooman/swift,apple/swift,rudkx/swift,ahoppen/swift,gregomni/swift,gregomni/swift,apple/swift,tkremenek/swift,ahoppen/swift,xwu/swift,benlangmuir/swift,apple/swift,parkera/swift