[stdlib] Moving the Array.filter to _ArrayProtocol

Resolves ambiguity in the following expression

  _ = Array(0..<10).lazy.flatMap { .some($0) }.filter { _ in false }

Fixes: <rdar://problem/32316948>

stdlib/public/core/Arrays.swift.gyb

@@ -1574,16 +1574,6 @@ extension ${Self} : RangeReplaceableCollection, _ArrayProtocol {
     }
   }
 
-  // Since RangeReplaceableCollection now has a version of filter that is less
-  // efficient, we should make the default implementation coming from Sequence
-  // preferred.
-  @_inlineable
-  public func filter(
-    _ isIncluded: (Element) throws -> Bool
-  ) rethrows -> [Element] {
-    return try _filter(isIncluded)
-  }
-
   //===--- algorithms -----------------------------------------------------===//
 
   @_inlineable