How to set path to the image instead of alt in media.php?

This should do the trick

add_filter('wp_get_attachment_image_attributes', 'change_alt_image', 10, 2);

function change_alt_image($attr, $attachment) {

$data_img = wp_get_attachment_image_src($attachment->ID, 'original', false);

    $attr['alt'] = esc_url($data_img[0]);

    return $attr;

}