Improve look/feel of premium block promos on WordPress.com

We've got a hand full of blocks on WP.com that require a specific plan. If you're on a lower plan, you'll see a prompt to upgrade in order to use these blocks. The design of these promo's could use some love.

#### Steps to reproduce the issue

1. Create a WordPress.com free account.
2. Add a page
3. Add one of the following blocks:

- Simple Payments
- Recurring Payments
- OpenTable
- Calendly

#### What I expected
Promo looks consistent, minimal, and well designed.

#### What happened instead

**Screenshots**

Here's what these promos look like now:

Reproduce the premium promo experience with a WordPress.com free account and inspect the implementations for the Simple Payments, Recurring Payments, OpenTable, and Calendly blocks. Compare their current presentations with the stated goal of a consistent, minimal design; done means the affected promos share a polished, consistent look across all four blocks.

Written by the indexing model from the issue text.