[move-only] Fix up a test slightly.

This test was taken from some generated SIL when the address checker ran
/before/ the object checker and before the address checker validated that the
object checker also didn't leave any copy_value. This is just cleaning up the
source as if the object checker ran on this specific function so the address
checker check doesn't trip.

Author: gottesmm

test/SILOptimizer/moveonly_addresschecker.sil

@@ -283,10 +283,8 @@ bb0(%arg : @owned $Klass):
   %21 = move_value [lexical] %19 : $Klass
   %22 = mark_must_check [no_implicit_copy] %21 : $Klass
   debug_value %22 : $Klass, let, name "k2"
-  %24 = copy_value %22 : $Klass
-  %25 = move_value %24 : $Klass
+  %25 = move_value %22 : $Klass
   destroy_value %25 : $Klass
-  destroy_value %22 : $Klass
   destroy_addr %1 : $*Klass
   dealloc_stack %0 : $*Klass
   %30 = tuple ()