Fix tests: "infix modifier required" and "operator modifier required" errors

compiler/testData/codegen/boxAgainstJava/callableReference/publicMutableField.kt

@@ -4,7 +4,7 @@ fun box(): String {
     val a = A()
     val f = A::field
     if (f.get(a) != 239) return "Fail 1: ${f.get(a)}"
-    f[a] = 42
+    f.set(a, 42)
     if (f.get(a) != 42) return "Fail 2: ${f.get(a)}"
     if (f.get(a) != 42) return "Fail 2: ${f.get(a)}"
     return "OK"

compiler/testData/codegen/boxAgainstJava/sam/adapters/operators/infixCall.java

@@ -1,5 +0,0 @@
-class JavaClass {
-    void doSomething(Runnable i) {
-        i.run();
-    }
-}

compiler/testData/codegen/boxAgainstJava/sam/adapters/operators/infixCall.kt

@@ -1,7 +0,0 @@
-fun box(): String {
-    val obj = JavaClass()
-
-    var v = "FAIL"
-    obj doSomething { v = "OK" }
-    return v
-}