wpcomsh: Remove Gutenberg site logo hotfix from 2021

[mreishus]

Proposed changes:

• Remove the hotfix for a bug in Gutenberg preventing updating a logo in the Customizer.
  • The changes were merged to Gutenberg here: Site Logo Block: update Site Logo block UI and option syncing WordPress/gutenberg#33179
  • We can verify the same code exists here: https://github.com/mreishus/gutenberg/blob/56bfef82bb93d2bba226e0631aed03eb16057cfd/packages/block-library/src/site-logo/index.php#L145-L155
  • I also removed this same one from simple sites with no problem here: D152692-code

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

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

Testing instructions:

• Go to '..'

[github-actions]

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[mreishus]

✔️ Verified that changing or the site logo in the customizer, on WoA, on a non-block theme updated the site logo used in blocks appropriately