Sharing: Mismatch in "Official buttons" preview on backend and ones on actual page

#### Steps to reproduce

- Start with a WordPress.com site or a self-hosted WordPress (WordPress.org) site with Jetpack installed, activated and setup
- Ensure `Sharing` module is enabled
- Visit `Settings` > `Sharing` on /wp-admin dashboard
- Enable a few services
- Be sure to choose `Official buttons` mode

#### What is expected

The `Live preview` buttons shown on this page (backend) matches the ones shown on the actual page on the frontend

#### What happens instead

The buttons are not the same for a few services

#### Screenshots

The one below is from /wp-admin dashboard

The one below is from the actual page

#### Notes

The buttons on https://wordpress.com/sharing/buttons matches the ones on the actual page though.

The buttons match fine for other three modes:

- Icon + text
- Icon only
- Text only

I stumbled upon this when I was testing https://github.com/Automattic/jetpack/issues/8883 and [from what I see](https://github.com/Automattic/jetpack/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+sharing+preview), there is no previous report.

Start by comparing the Sharing settings screen's Official buttons live preview with the buttons rendered on an actual page, using the WordPress.com sharing/buttons page as a reference. Trace the preview and frontend entry points, then verify that Official buttons match for the affected services without changing the other three modes.

Written by the indexing model from the issue text.