CKEditor 5 resize unit changed from % to px

Previously the Drupal CKEditor 5 was using % value. Values with % result in an inconsistent experience because the size of the image would be calculated based on the container width. This could result in problems with captioned images, or when the container width doesn't match expectations for other reasons. The % also results in an inconsistent experience with some commonly used styles for making images behave responsive.

For these reasons, images are now resized using px unit. Any previously resized images that are using % will remain using % until the image is resized again in CKEditor 5.