Use LifetimeTracked for Array.popLast test (swiftlang#14334)

Author: airspeedswift

validation-test/stdlib/Arrays.swift.gyb

@@ -1524,12 +1524,12 @@ ArrayTestSuite.test("${Kind}/popLast") {
   }
 
   do {
-    var popped = [Int]()
-    var a: ${Kind}<Int> = [1010, 2020, 3030]
+    var popped = [LifetimeTracked]()
+    var a: ${Kind} = [LifetimeTracked(1010), LifetimeTracked(2020), LifetimeTracked(3030)]
     while let element = a.popLast() {
       popped.append(element)
     }
-    expectEqualSequence([1010, 2020, 3030], popped.reversed())
+    expectEqualSequence([1010, 2020, 3030], popped.reversed().lazy.map({ $0.value }))
     expectTrue(a.isEmpty)
   }
 }