Remove _partitioned and use it inline (since it’s no longer used by the Collection implementation

Author: mdznr

Sources/Algorithms/Partition.swift

@@ -240,13 +240,6 @@ extension Sequence {
   @inlinable
   public func partitioned(
     _ belongsInSecondCollection: (Element) throws -> Bool
-  ) rethrows -> ([Element], [Element]) {
-    return try _partitioned(belongsInSecondCollection)
-  }
-  
-  @inlinable
-  internal func _partitioned(
-    _ belongsInSecondCollection: (Element) throws -> Bool
   ) rethrows -> ([Element], [Element]) {
     var lhs = Array<Element>()
     var rhs = Array<Element>()