Embed Block: Retry does not work for URLs with a trailing slash

[t-hamano]

Description

This is the regression discovered in this comment: #57969 (comment)

If the Embed block fails to embed a URL with a trailing slash, as shown in this test, it should remove the slash and try to embed it again. This has been implemented in #14705, but for some reason it doesn't work now so we had to skip testing it.

Step-by-step reproduction instructions

• Insert an Embed Block or a Twitter Block.
• Enter the Twitter URL with a trailing slash: https://twitter.com/WordPress/
  • Expected: The URL should be converted to https://twitter.com/WordPress without the trailing slash, and Twitter should be embedded successfully.
  • Actual: The embedding should fail and the URL should remain the same.

Screenshots, screen recording, code snippet

675532d2fe002004c7dffc7e50182629.mp4

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes