chore(analytics): Remove cSettings from Package.swift

[koji-1009]

Description

This PR removes unnecessary cSettings from the Package.swift file for the firebase_analytics package.

https://developer.apple.com/documentation/packagedescription/csetting
https://docs.flutter.dev/packages-and-plugins/swift-package-manager/for-plugin-authors

ref #17403

Related Issues

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Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]).
This will ensure a smooth and quick review process. Updating the pubspec.yaml and changelogs is not required.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
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• I read and followed the Flutter Style Guide.
• I signed the CLA.
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Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change.
• No, this is not a breaking change.

[SelaseKay]

LGTM!