KT-11912 String interpolation is not converted to ${} form when accessing this.property

#KT-11912 Fixed

idea/idea-completion/testData/handlers/basic/stringTemplate/AfterThisDot.kt

@@ -0,0 +1,6 @@
+fun String.foo() {
+    val s = "$this.<caret>"
+}
+
+// ELEMENT: equals
+// TAIL_TEXT: "(other: Any?)"

idea/idea-completion/testData/handlers/basic/stringTemplate/AfterThisDot.kt.after

@@ -0,0 +1,6 @@
+fun String.foo() {
+    val s = "${this.equals(<caret>)}"
+}
+
+// ELEMENT: equals
+// TAIL_TEXT: "(other: Any?)"