Update method signatures in RedBlackTree to accept correct Iterators (#24085)

Fix errors in #24081

Take `immutable.TreeSet.from` as an example, the parameter is tracked: `it: IterableOnce[E]^`. After pattern match, `ss` should be `SortedSet[E]^{it}`. Calling `iterator` will return an `Interator^{ss}`, which is tracked as well. However, `fromOrderedKeys` only accepts non-tracked `Interator`, and causes error.

The fix updates`fromOrderedKeys` and `fromOrderedEntries`.

Author: noti0na1

library/src/scala/collection/immutable/RedBlackTree.scala

@@ -940,7 +940,7 @@ private[collection] object RedBlackTree {
   }
 
   /** Build a Tree suitable for a TreeSet from an ordered sequence of keys */
-  def fromOrderedKeys[A](xs: Iterator[A], size: Int): Tree[A, Null] = {
+  def fromOrderedKeys[A](xs: Iterator[A]^, size: Int): Tree[A, Null] = {
     val maxUsedDepth = 32 - Integer.numberOfLeadingZeros(size) // maximum depth of non-leaf nodes
     def f(level: Int, size: Int): Tree[A, Null] = size match {
       case 0 => null
@@ -956,7 +956,7 @@ private[collection] object RedBlackTree {
   }
 
   /** Build a Tree suitable for a TreeMap from an ordered sequence of key/value pairs */
-  def fromOrderedEntries[A, B](xs: Iterator[(A, B)], size: Int): Tree[A, B] = {
+  def fromOrderedEntries[A, B](xs: Iterator[(A, B)]^, size: Int): Tree[A, B] = {
     val maxUsedDepth = 32 - Integer.numberOfLeadingZeros(size) // maximum depth of non-leaf nodes
     def f(level: Int, size: Int): Tree[A, B] = size match {
       case 0 => null

library/src/scala/collection/mutable/RedBlackTree.scala

@@ -605,7 +605,7 @@ private[collection] object RedBlackTree {
   // building
 
   /** Build a Tree suitable for a TreeSet from an ordered sequence of keys */
-  def fromOrderedKeys[A](xs: Iterator[A], size: Int): Tree[A, Null] = {
+  def fromOrderedKeys[A](xs: Iterator[A]^, size: Int): Tree[A, Null] = {
     val maxUsedDepth = 32 - Integer.numberOfLeadingZeros(size) // maximum depth of non-leaf nodes
     def f(level: Int, size: Int): Node[A, Null] = size match {
       case 0 => null
@@ -624,7 +624,7 @@ private[collection] object RedBlackTree {
   }
 
   /** Build a Tree suitable for a TreeMap from an ordered sequence of key/value pairs */
-  def fromOrderedEntries[A, B](xs: Iterator[(A, B)], size: Int): Tree[A, B] = {
+  def fromOrderedEntries[A, B](xs: Iterator[(A, B)]^, size: Int): Tree[A, B] = {
     val maxUsedDepth = 32 - Integer.numberOfLeadingZeros(size) // maximum depth of non-leaf nodes
     def f(level: Int, size: Int): Node[A, B] = size match {
       case 0 => null