Sharing block: remove check for existing block in post content

[jeherve]

Proposed changes:

This is no longer necessary after some improvements to the Block Hooks API.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

• N/A

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

• No

Testing instructions:

• Start with a site that's connected to WordPress.com, using a block-based theme, and where the Sharing module is not active.
• Enable auto-addition of the sharing block to single post templates: wp option update jetpack_sharing_buttons_auto_add 1
• Visit a single post ; you should see sharing buttons being added at the bottom of the post.
• Now go to Appearance > Editor > Templates > Single Posts
• Add a sharing block and configure it, right below the post title for example.
• Remove any sharing block you may see at the bottom of the post content.
• Save your changes.
• Now visit a single post again ; you should only see the new sharing block you added to the top of the template, under the post title.

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

• ✅ Include a description of your PR changes.
  
• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

---

The e2e test report can be found here. Please note that it can take a few minutes after the e2e tests checks are complete for the report to be available.

---

Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Choose a review path based on your changes:
   • A. Team Review: add the "[Status] Needs Team Review" label
     • For most changes, including minor cross-team impacts.
     • Example: Updating a team-specific component or a small change to a shared library.
   • B. Crew Review: add the "[Status] Needs Review" label
     • For significant changes to core functionality.
     • Example: Major updates to a shared library or complex features.
   • C. Both: Start with Team, then request Crew
     • For complex changes or when you need extra confidence.
     • Example: Refactor affecting multiple systems.
3. Get at least one approval before merging.

Still unsure? Reach out in #jetpack-developers for guidance!

---

Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

• WordPress.com Simple releases happen daily.
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly. The next release is scheduled for September 3, 2024 (scheduled code freeze on September 2, 2024).

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WordPress.com Simple site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin, and enable the update/sharing-block-check-content branch.

• To test on Simple, run the following command on your sandbox:

  bin/jetpack-downloader test jetpack update/sharing-block-check-content
  

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[coder-karen]

Tests well 👍