Sharing: fix icon font display

[jeherve]

This is a follow-up of #31873.

Proposed changes:

The icon font's base64-encoded string wasn't correct the last time around. this should fix it.

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

• p1689640150536069-slack-CBG1CP4EN
• Social Menu & Social Media Icons: Add Threads support #31873 (comment)

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

• No

Testing instructions:

• Go to Jetpack > Settings > Sharing
• Enable sharing buttons
• Go to Settings > Sharing, and enable a few buttons
• Check that they look good on the frontend.
• Check that on wpcom simple too.

[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 > Jetpack and enable the fix/icon-font-post-threads branch.

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

  bin/jetpack-downloader test jetpack fix/icon-font-post-threads
  

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

[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.
  
• ✅ All commits were linted before commit.
  
• ✅ 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 🤖

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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.

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Once your PR is ready for review, check one last time that all required checks (other than "Required review") appearing at the bottom of this PR are passing or skipped.
Then, add the "[Status] Needs Team Review" label and ask someone from your team review the code. Once reviewed, it can then be merged.
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Jetpack plugin:

• Next scheduled release: August 1, 2023.
• Scheduled code freeze: July 25, 2023.

[sdixon194]

Patched 12.4-a.5 with this and it worked just great.