Remove backend tests on old inference

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

compiler/testData/ir/irText/expressions/funInterface/castFromAny.kt

@@ -1,5 +1,4 @@
 // FIR_IDENTICAL
-// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 fun interface KRunnable {
     fun invoke()
@@ -9,4 +8,3 @@ fun test(a: Any?) {
     a as () -> Unit
     KRunnable(a).invoke()
 }
-