[IR] Drop "leaf/non-leaf" comment from generated IR classes

As it is not much useful, and the current wording does not represent its
intended wording.

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/AbstractElementPrinter.kt

@@ -22,8 +22,6 @@ abstract class AbstractElementPrinter<Element : AbstractElement<Element, Field,
     context(ImportCollector)
     protected abstract fun SmartPrinter.printAdditionalMethods(element: Element)
 
-    protected open fun defaultElementKDoc(element: Element): String? = null
-
     protected open val separateFieldsWithBlankLine: Boolean
         get() = false
 
@@ -35,7 +33,7 @@ abstract class AbstractElementPrinter<Element : AbstractElement<Element, Field,
         printer.run {
             val kind = element.kind ?: error("Expected non-null element kind")
 
-            printKDoc(element.extendedKDoc(defaultElementKDoc(element)))
+            printKDoc(element.extendedKDoc())
             print(kind.title, " ", element.typeName)
             print(element.params.typeParameters())
 

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/printer/printUtils.kt

@@ -85,8 +85,8 @@ fun SmartPrinter.printKDoc(kDoc: String?) {
     println(" */")
 }
 
-fun AbstractElement<*, *, *>.extendedKDoc(defaultKDoc: String? = null): String = buildString {
-    val doc = kDoc ?: defaultKDoc
+fun AbstractElement<*, *, *>.extendedKDoc(): String = buildString {
+    val doc = kDoc
     if (doc != null) {
         appendLine(doc)
         appendLine()