[K/N] Change test to make aggregate green.

The test is using error suppressing, so breaking it is fine.


^KT-62015

kotlin-native/backend.native/tests/framework/stdlib/stdlib.kt

@@ -79,9 +79,9 @@ fun testSet(set: Set<String>) {
     assertFalse(set.contains("h"))
     assertFalse(setAny.contains(1))
 
-    set as kotlin.native.internal.KonanSet<String> // Smart cast to access getElement below.
-    assertEquals("a", set.getElement("a"))
-    assertNull(set.getElement("aa"))
+    val konanSet = set as kotlin.native.internal.KonanSet<String>
+    assertEquals("a", konanSet.getElement("a"))
+    assertNull(konanSet.getElement("aa"))
     assertNull((setAny as kotlin.native.internal.KonanSet<Any?>).getElement(1))
 }