Remove backend tests on old inference

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

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

@@ -1,5 +1,3 @@
-// !LANGUAGE: +NewInference +FunctionReferenceWithDefaultValueAsOtherType +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
-
 fun interface IFoo {
     fun foo(i: Int)
 }
@@ -18,4 +16,4 @@ fun withVarargOfInt(vararg xs: Int) = ""
 
 fun testAdaptedCR() {
     useVararg(::withVarargOfInt)
-}
+}