Remove backend tests on old inference

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

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

@@ -1,5 +1,3 @@
-// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
-
 // This test should check argument coercion between the SAM and the lambda.
 // For now it checks that Char is boxed in JS
 
@@ -40,4 +38,4 @@ fun box(): String {
     if (c6 !is Char || c6 != '6') return "fail6"
 
     return "OK"
-}
+}