[Shipping labels] Remove label paper size from shipment details to match updated designs

[rachelmcr]

Part of: #14044

Description

This removes the label paper size dropdown menu from the shipment details bottom sheet, in the new Woo Shipping label creation flow, per the design discussion in pe5pgL-5rm-p2#comment-4584.

Testing information

1. Install and set up the Woo Shipping extension on your store.
2. Build and run the app with the revampedShippingLabelCreation feature flag enabled.
3. Create an order with the processing status and at least one physical product.
4. In the order details, select "Create Shipping Label."
5. Confirm the bottom sheet appears and is collapsed with the "Shipment details" label.
6. Tap or drag the bottom sheet to expand it, and confirm the expected bottom sheet UI is visible.
7. Confirm the "Mark as complete" toggle and purchase button are at the bottom of the screen, and the label paper size menu is removed.

Screenshots

Before	After

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• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 20.6. 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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[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	pr14055-6d387ec
	Version	20.5
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	6d387ec
	App Center Build	WooCommerce - Prototype Builds #11034

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