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

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