Remove backend tests on old inference

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

compiler/testData/codegen/box/callableReference/adaptedReferences/inlineVararg.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// !LANGUAGE: +NewInference
 // WITH_RUNTIME
 
 inline fun foo(mkString: (Char, Char) -> String): String =
@@ -10,4 +9,4 @@ fun bar (vararg xs: Char) =
         xs.concatToString()
 
 fun box(): String = foo(::bar)
-// -> { a, b -> bar(a, b) }
+// -> { a, b -> bar(a, b) }