Twenty Twenty-One: twenty_twenty_one_get_attachment_image_attributes affects the admin panel

[denisco]

Twenty Twenty-One v1.1

The function twenty_twenty_one_get_attachment_image_attributes affects the attributes of images in the admin panel.

I faced this problem while developing a plugin for comments (I attached a screenshot).

I think we need to add an additional condition to reduce the effect of this function.

[SergeyBiryukov]

In 49930:

Twenty Twenty-One: Make sure filtering attachment image attributes only affects front end and not the admin area.

Props denisco.
Fixes #52212.

[SergeyBiryukov]

Reopening for 5.6.1 consideration.