Blocks: deprecate the server-side rendered nudges

[jeherve]

Changes proposed in this Pull Request:

We've updated the way we display nudges in #16611, so it may make sense to move away from our custom implementation to simplify things a bit with our build.

This PR's counterpart was #13070, where most of this was introduced.

I'm now trying to:

• deprecate the upgrade_nudge method in the Gutenberg class. It is not used anymore since Premium Blocks: Implement the new design #16611, where we moved to a new upgrade nudge design for the blocks.
• switch back to simple notice for the Pay with Paypal shortcode. Since the block does not rely on shortcodes anymore, and since the Calypso classic editor has been deprecated, I can't really think of many ways ways a site owner can end up inserting a Pay With PayPal shortcode on their site today. We may be able to simplify some things by moving back to a simple notice here.
• Deprecate methods that are not in use anymore.
• Remove server-side rendered upgrade nudge

Jetpack product discussion

• Internal reference: p1607628394297200-slack-CBG1CP4EN

Does this pull request change what data or activity we track or use?

• No

Testing instructions:

This will require some testing of:

• the Pay With PayPal block (with a free plan and a paid plan)
• the Pay With PayPal shortcode,
• and all the blocks that use the upgrade nudge (Pay with PayPal, Donations, Social Previews, ...). You can display that nudge by adding this filter on a site with a free plan, connected to WordPress.com: add_filter( 'jetpack_block_editor_enable_upgrade_nudge', '__return_true' );

Proposed changelog entry for your changes:

• N/A

[test-case-reminder]

Here are some suggested test cases for this PR.

Gutenberg extensions

• Use Core's block editor
• Use latest stable Gutenberg plugin

Blocks

• Tiled Gallery
• Business Hours
• Calendly
• Form
• Contact Info
• Eventbrite
• Google calendar
• Mailchimp
• Map
• OpenTable
• Pinterest
• Podcast player
• Star rating
• Recurring Payments
• Repeat Visitor
• Revue
• Simple Payments
• Slideshow

Extensions

• Publicize
• Likes

If you think that suggestions should be improved please edit the configuration file here. You can also modify/add test-suites to be used in the configuration file.

[jetpackbot]

Scheduled Jetpack release: January 12, 2021.
Scheduled code freeze: January 4, 2021

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Generated by 🚫 dangerJS against 8c35c98

[ockham]

Nice, this would indeed allow us to get rid of a ton of code, and unblock the wordpress monorepo upgrade (#16763), without even needing the preparatory steps (#18024) which were all related to the upgrade nudge's server-side stuff. cc/ @anomiex @brbrr

I don't know exactly how the upgrade nudge has changed since I implemented it, so I'm not totally familiar how (and under what circumstances) it works now -- meaning I can't really approve that aspect of the PR comfortably. I'll just note that the main reason for #16611 was to have the upgrade nudge rendered on the frontend (for logged-in users). It might be worth testing that nothing is broken there per this PR.

LMK if you'd like me to review the technical removal bits 🙂

[jeherve]

Putting this on hold for now, as per pcjTuq-8U-p2