Remove backend tests on old inference

Also remove any mentions of NewInference, and rename some tests.

compiler/testData/ir/irText/expressions/callableReferences/adaptedExtensionFunctions.kt

@@ -1,5 +1,3 @@
-// !LANGUAGE: +NewInference +FunctionReferenceWithDefaultValueAsOtherType
-
 fun use(f: C.(Int) -> Unit) {}
 
 class C
@@ -20,4 +18,4 @@ fun testExtensionDefault() {
 
 fun testExtensionBoth() {
     use(C::extensionBoth)
-}
+}