Mailchimp Block: Consent text and customize option

It's pretty common to have a subscription form in a confined space like a footer, for example:


As you can see above, the lengthy consent text from the block makes it look tall and unpleasant. I had a look at [the Mailchimp's support page](https://mailchimp.com/help/add-a-signup-form-to-your-website/#Form_options) where we can see examples of their embed forms, and I didn't see the consent text around the form as default. That makes me wonder if we can remove it so that it could be more compact.

If we really have to have it then, can we shorten it? Can we provide a font size option for the text? Or can we change it to a notice that only appears in a confirmation step? I almost think an extra step would be better than the current state :)

Also, it'd be good to provide customize options just like the subscription block as well.

Lastly, the message that appears after adding an email doesn't look good either. We should remove the background on the text.


cc @apeatling @ianstewart @alaczek

No file, test, or entry point is named. Start by locating the Mailchimp Block implementation and its existing customization controls, then review the consent text and post-submission message against the screenshots. The requested behavior needs agreement before implementation; done should be defined by an accepted scope and corresponding UI changes.

Written by the indexing model from the issue text.