Clean up test skips after KT-17137

We need to clean these up since primitive array `is` checks work now

(cherry picked from commit b413e9ef51606c51ebfb21bd7ff646b0fb75470a)

compiler/testData/codegen/box/arrays/arrayInstanceOf.kt

@@ -22,8 +22,5 @@ fun test(createIntNotLong: Boolean): String {
 }
 
 fun box(): String {
-    // Only run this test if primitive array `is` checks work (KT-17137)
-    if ((intArrayOf() as Any) is Array<*>) return "OK"
-
     return test(true) + test(false)
 }