Remove backend tests on old inference

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

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

@@ -1,5 +1,4 @@
 // FIR_IDENTICAL
-// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 fun interface Foo {
     fun invoke(): String
@@ -7,4 +6,4 @@ fun interface Foo {
 
 fun foo(f: Foo) = f.invoke()
 
-fun test() = foo { "OK" }
+fun test() = foo { "OK" }