Fix incorrect image upload error message

[0nko]

This PR fixes the wrong private site status message for self-hosted sites, which prevents the app from uploading images.

To test:

1. Create a self-hosted site with WooCommerce but without installing Jetpack or connecting a WP.com user using JCP
2. Log in to the app
3. Start creating a product
4. Verify the image uploading is available

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[wpmobilebot]

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

	App Name	WooCommerce Android
	Flavor	Jalapeno
	Build Type	Debug
	Commit	dcd4c0c
	Direct Download	woocommerce-prototype-build-pr11493-dcd4c0c.apk

[hichamboushaba]

Thanks for taking care of this @0nko, it works well.

Before merging this, it seems to me this is a serious bug, shouldn't we include it in the current beta version?

[0nko]

Thanks @hichamboushaba. I've rebased the branch onto release/18.6

[hichamboushaba]

Thanks @hichamboushaba. I've rebased the branch onto release/18.6

Thanks @0nko, there is a failing unit test that's preventing the merge.