Summary

This PR reverts the Instant Sharing's default toggle back to the main settings. It will work for both Classic and Block Editor.

Test instructions

• In Block Editor and ClassicEditor:
  • A new post should always respect the option and should have toggled enabled/disabled by default based on the option.
  • For published posts, it should always be disabled by default.

Check before Pull Request is ready:

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

Closes https://github.com/Codeinwp/tweet-old-post-pro/issues/614.