Remove the version of fail.kt that was "hacked" for JS IR BE tests

js/js.translator/testData/_commonFiles/fail.kt

@@ -2,4 +2,7 @@ package kotlin
 // This file should be excluded from tests using StdLib, as these methods conflict with corresponding methods from kotlin.test
 // see StdLibTestBase.removeAdHocAssertions
 
-fun fail(message: String? = null) = js("throw new Error(message)")
+fun fail(message: String? = null): Nothing {
+    js("throw new Error(message)")
+    null!!
+}

js/js.translator/testData/_commonFiles/fail_hacked.kt

@@ -1,7 +0,0 @@
-package kotlin
-// This file should be excluded from tests using StdLib, as these methods conflict with corresponding methods from kotlin.test
-// see StdLibTestBase.removeAdHocAssertions
-
-fun fail(message: String? = null): Nothing {
-    null!!
-}