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

compiler/testData/codegen/box/properties/kt4383.kt

@@ -1,7 +1,7 @@
 import kotlin.reflect.KProperty
 
 class D {
-    fun getValue(a: Any, p: KProperty<*>) { }
+    operator fun getValue(a: Any, p: KProperty<*>) { }
 }
 
 object P {

compiler/testData/codegen/box/properties/primitiveOverrideDelegateAccessor.kt

@@ -1,8 +1,8 @@
 import kotlin.reflect.KProperty
 
 class Holder(var value: Int) {
-    fun getValue(that: Any?, desc: KProperty<*>) = value
-    fun setValue(that: Any?, desc: KProperty<*>, newValue: Int) { value = newValue }
+    operator fun getValue(that: Any?, desc: KProperty<*>) = value
+    operator fun setValue(that: Any?, desc: KProperty<*>, newValue: Int) { value = newValue }
 }
 
 interface R<T: Comparable<T>> {