[Local catalog] End development approach to database migrations

[joshheald]

Description

This PR removes the development affordance for migrations, which deleted previous schemas whenever there was a change.

Now that we're ready to release local catalog, future schema changes should use a migration.

Test Steps

Launch the app on a device that you've used it on before, confirm you can open local catalog stores in POS

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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.

[wpmobilebot]

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

	App Name	WooCommerce iOS Prototype
	Build Number	pr16394-0af49a2
	Version	23.7
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	0af49a2
	Installation URL	5ogb35sinn2oo

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

[iamgabrielma]

LGTM! 🎉