Remove backend tests on old inference

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

compiler/testData/ir/irText/expressions/sam/genericSamProjectedOut.kt.txt

@@ -1,4 +1,5 @@
-fun test(a: SomeJavaClass<out String>) {
+fun test() {
+  var a: SomeJavaClass<out String> = SomeJavaClass<String>()
   a.someFunction(hello = local fun <anonymous>(it: @FlexibleNullability String?) {
     return Unit
   }
@@ -6,9 +7,17 @@ fun test(a: SomeJavaClass<out String>) {
   a.plus(hello = local fun <anonymous>(it: @FlexibleNullability String?) {
     return Unit
   }
- /*-> @FlexibleNullability Hello<Nothing>? */)
+ /*-> @FlexibleNullability Hello<Nothing>? */) /*~> Unit */
   a.get(hello = local fun <anonymous>(it: @FlexibleNullability String?) {
     return Unit
   }
  /*-> @FlexibleNullability Hello<Nothing>? */)
+  a = a.plus(hello = local fun <anonymous>(it: @FlexibleNullability String?) {
+    return Unit
+  }
+ /*-> @FlexibleNullability Hello<Nothing>? */) /*!! SomeJavaClass<out @FlexibleNullability String?> */
+  a.set(i = 0, hello = local fun <anonymous>(it: @FlexibleNullability String?) {
+    return Unit
+  }
+ /*-> @FlexibleNullability Hello<Nothing>? */)
 }