[google_maps_flutter] Remove duplicated privacy manifest entries

[stuartmorgan-g]

Google Maps SDK 8.4 didn't include a privacy manifest, just instructions for clients to download and manually add one. Rather than push that requirement onto plugin clients, we duplicated all of the relevant manifest entries into the plugin's manifest.

Starting with 9.0.0 the Google Maps SDK includes its own manifest, so we no longer need to bundle it ourselves when we know that the SDK is 9+. Since that's the case for the SDK-specific copies of the implementation package, we can remove it there, while leaving it in google_maps_flutter_ios (which can still resolve to 8.4).

Fixes flutter/flutter#146838

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[gemini-code-assist]

Code Review

This pull request removes duplicated privacy manifest entries from the PrivacyInfo.xcprivacy files in both the google_maps_flutter_ios_sdk9 and google_maps_flutter_ios_sdk10 packages. Additionally, the package versions are bumped to 2.18.3 and the changes are documented in their respective changelogs. There are no review comments, and I have no feedback to provide.