Delete more unused WordPress- Authenticator and Kit sources

[mokagio]

Note

Waiting for #15140 to go through code review and land so that we can verify green CI here with more confidence.

Follow up to #15000.

See also #14790, #14794 , #14816, #14821.

[dangermattic]

	2 Warnings
⚠️	View files have been modified, but no screenshot or video is included in the pull request. Consider adding some for clarity.
⚠️	This PR is larger than 300 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

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[wpmobilebot]

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

	App Name	WooCommerce iOS
	Build Number	pr15142-d2d5488
	Version	21.7
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	d2d5488
	App Center Build	WooCommerce - Prototype Builds #12994

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