Update TS docs for contentInsetAdjustmentBehavior (#50069)

Summary:
Update the TS docs to reflect the default value for `contentInsetAdjustmentBehavior`. The TS docs suggest it will be `automatic` however it's actually `never`.

The default behaviour is correctly specified in the JS docs: https://github.com/facebook/react-native/blob/850760ab6112d1f38a5a9014282ae5186ab814d6/packages/react-native/Libraries/Components/ScrollView/ScrollView.js#L306

It's also documented as the default in the native module: https://github.com/facebook/react-native/blob/main/packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTEnhancedScrollView.mm#L34

## Changelog:

[General] [Fixed] - Fix TS docs for `contentInsetAdjustmentBehavior`

<!-- Help reviewers and the release process by writing your own changelog entry.

Pull Request resolved: https://github.com/facebook/react-native/pull/50069

Reviewed By: NickGerleman

Differential Revision: D71491433

Pulled By: lunaleaps

fbshipit-source-id: 08b3f273824be570589095bf0640d7d0b7c93e7d

packages/react-native/Libraries/Components/ScrollView/ScrollView.d.ts

@@ -405,7 +405,7 @@ export interface ScrollViewPropsIOS {
 
   /**
    * This property specifies how the safe area insets are used to modify the content area of the scroll view.
-   * The default value of this property must be 'automatic'. But the default value is 'never' until RN@0.51.
+   * The default value of this property is "never".
    */
   contentInsetAdjustmentBehavior?:
     | 'automatic'

packages/react-native/Libraries/Components/ScrollView/ScrollView.js

@@ -300,7 +300,7 @@ export type ScrollViewPropsIOS = $ReadOnly<{
   /**
    * This property specifies how the safe area insets are used to modify the
    * content area of the scroll view. The default value of this property is
-   * "never". Available on iOS 11 and later.
+   * "never".
    * @platform ios
    */
   contentInsetAdjustmentBehavior?: ?(