"field": deprecated warnings introduced, compiler tests migrated to the new syntax

compiler/testData/codegen/box/operatorConventions/incDecOnObject.kt

@@ -16,11 +16,11 @@ class Z {
 
     public var prop: X = X(0)
         get()  {
-            counter++; return $prop
+            counter++; return field
         }
         set(a: X) {
             counter++
-            $prop = a;
+            field = a;
         }
 }
 

compiler/testData/codegen/box/operatorConventions/kt4152.kt

@@ -1,19 +1,19 @@
 public var inc: Int = 0;
 
 public var propInc: Int = 0
-    get() {inc++; return $propInc}
+    get() {inc++; return field}
     set(a: Int) {
         inc++
-        $propInc = a
+        field = a
     }
 
 public var dec: Int = 0;
 
 public var propDec: Int = 0;
-    get() { dec--; return $propDec}
+    get() { dec--; return field}
     set(a: Int) {
         dec--
-        $propDec = a
+        field = a
     }
 
 fun box(): String {