Remove unused appRatingUtility from AppEnvironment

[mokagio]

I noticed this unused property while working on #24351.

I'll acknowledge that we should ditch AppEnvironment altogether, but short of time to address that, this at least reduces its surface area.

Part of #24165.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 25.9. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

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📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	26830
	Version	PR #24352
	Bundle ID	com.jetpack.alpha
	Commit	ec6ae5a
	Installation URL	7p7803nqq2rm0

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	26830
	Version	PR #24352
	Bundle ID	org.wordpress.alpha
	Commit	ec6ae5a
	Installation URL	1k7la7vnngs6g

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.