[Test] Reenabled SILOpt/shrink_borrow_scope.
[Test] Reenabled SILOpt/shrink_borrow_scope.

LexicalDestroyFolding allows us to elide the spurious retain/release
that was being tested here.

rdar://87255563

atrick/swift,atrick/swift,benlangmuir/swift,benlangmuir/swift,gregomni/swift,benlangmuir/swift,roambotics/swift,JGiola/swift,ahoppen/swift,ahoppen/swift,gregomni/swift,gregomni/swift,rudkx/swift,roambotics/swift,apple/swift,rudkx/swift,atrick/swift,JGiola/swift,roambotics/swift,apple/swift,apple/swift,roambotics/swift,gregomni/swift,apple/swift,JGiola/swift,glessard/swift,atrick/swift,ahoppen/swift,ahoppen/swift,gregomni/swift,glessard/swift,rudkx/swift,apple/swift,glessard/swift,glessard/swift,roambotics/swift,roambotics/swift,apple/swift,glessard/swift,glessard/swift,atrick/swift,JGiola/swift,benlangmuir/swift,gregomni/swift,rudkx/swift,JGiola/swift,ahoppen/swift,JGiola/swift,ahoppen/swift,benlangmuir/swift,rudkx/swift,benlangmuir/swift,atrick/swift,rudkx/swift