Fix NSPrivacyCollectedDataTypes array in privacy manifest (#49041)

In #48951 `NSPrivacyCollectedDataTypes` is an array with an empty dictionary, but the privacy report wants an empty array or it errors:

<img width="523" alt="Screenshot 2023-12-14 at 10 02 52�AM" src="https://github.com/flutter/flutter/assets/682784/a128b384-db2f-49d7-8b71-7965f2826de8">

When this is fixed the privacy report is blank, but that seems to be an Xcode bug?  Will investigate.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: jmagman

shell/platform/darwin/ios/framework/PrivacyInfo.xcprivacy

@@ -7,9 +7,7 @@
 	<key>NSPrivacyTrackingDomains</key>
 	<array/>
 	<key>NSPrivacyCollectedDataTypes</key>
-	<array>
-		<dict/>
-	</array>
+	<array/>
 	<key>NSPrivacyAccessedAPITypes</key>
 	<array>
 		<dict>