Shorten References: Do not shorten qualified expression if receiver values are changed

#KT-5180 Fixed

idea/testData/refactoring/extractFunction/parameters/extractThis/explicitThisInExtension.kt.after

@@ -6,5 +6,5 @@ fun Z.foo(): Int {
 }
 
 fun Z.i(): Int {
-    return a
+    return this.a
 }

idea/testData/refactoring/extractFunction/parameters/extractThis/implicitAndExplicitThisInExtension.kt.after

@@ -6,5 +6,5 @@ fun Z.foo(): Int {
 }
 
 fun Z.i(): Int {
-    return a + a
+    return this.a + a
 }