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

Props denisco.
Fixes #52212.

git-svn-id: https://develop.svn.wordpress.org/trunk@49930 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-content/themes/twentytwentyone/inc/template-functions.php

@@ -417,6 +417,10 @@ add_filter( 'the_password_form', 'twenty_twenty_one_password_form' );
  */
 function twenty_twenty_one_get_attachment_image_attributes( $attr, $attachment, $size ) {
 
+	if ( is_admin() ) {
+		return $attr;
+	}
+
 	if ( isset( $attr['class'] ) && false !== strpos( $attr['class'], 'custom-logo' ) ) {
 		return $attr;
 	}