Deprecate file_managed_file_submit form submit handler and move to \Drupal\file\Element\ManagedFile

I have applied the MR on a fresh Drupal 11.x site and confirmed the following through the UI:

• Created a content type with a File field and tested upload and remove functionality. Everything worked as expected.
• Repeated the test with an Image field — both upload and remove actions work correctly.
• Verified behavior for single and multi-value fields.
• Tested required field validation by removing the uploaded file — validation triggers as expected.
• Confirmed no errors in the PHP logs or JavaScript console.
• Verified that file_managed_file_submit() is now deprecated and the logic is moved to \Drupal\file\Element\ManagedFile::submit(), maintaining BC correctly.
• Everything works as expected, and the code looks clean and standards-compliant.

Marking this issue RTBC.

Thanks!

The Needs Review Queue Bot → tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.