Extract property: do not add unnecessary extension receiver

#KT-24615 Fixed

idea/testData/refactoring/introduceProperty/kt24615.kt

@@ -0,0 +1,9 @@
+// EXTRACTION_TARGET: property with getter
+
+open class Base(protected val i: Int)
+
+class Impl(i: Int) : Base(i) {
+    fun foo(): Int {
+        return <selection>2 + 3 + i</selection>
+    }
+}

idea/testData/refactoring/introduceProperty/kt24615.kt.after

@@ -0,0 +1,12 @@
+// EXTRACTION_TARGET: property with getter
+
+open class Base(protected val i: Int)
+
+class Impl(i: Int) : Base(i) {
+    private val i: Int
+        get() = 2 + 3 + i
+
+    fun foo(): Int {
+        return i
+    }
+}