Remove backend tests on old inference

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

compiler/testData/codegen/box/funInterface/multimodule.kt

@@ -1,5 +1,3 @@
-// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
-
 // MODULE: m1
 // FILE: m1.kt
 
@@ -42,4 +40,4 @@ fun box(): String {
     if (rn2Inline { "inline" } != "inline") return "fail 4"
 
     return rn2 { "OK" }
-}
+}