Fix default value for scrollView.contentInsetAdjustmentBehavior

Summary:
Changelog: [internal]

The dafault UIKit value of `UIScrollView.contentInsetAdjustmentBehavior` is automatic. Fabric had incorrect value never.

source: https://developer.apple.com/documentation/uikit/uiscrollview/2902261-contentinsetadjustmentbehavior?language=objc

This was causing bug for one navigation library that's migrating to Fabric: reactwg/react-native-new-architecture#43 (comment)

Reviewed By: javache

Differential Revision: D37881453

fbshipit-source-id: 290ae428a720f00ed61f2a3e5c2c9bbf54e1ac6e

ReactCommon/react/renderer/components/scrollview/ScrollViewProps.h

@@ -63,7 +63,7 @@ class ScrollViewProps final : public ViewProps {
   bool snapToStart{true};
   bool snapToEnd{true};
   ContentInsetAdjustmentBehavior contentInsetAdjustmentBehavior{
-      ContentInsetAdjustmentBehavior::Never};
+      ContentInsetAdjustmentBehavior::Automatic};
   bool scrollToOverflowEnabled{false};
 
 #pragma mark - DebugStringConvertible