Check if we can remove the '#graphql_element_decoded' workaround

Problem/Motivation

We are storing an additional "#graphql_element_decoded" property on all Webform elements in \Drupal\graphql_webform\Plugin\GraphQL\DataProducer\WebformElements but it is unclear why this is needed. According to the documentation it is supposedly needed to read the description property, but this is available on the original element so we don't need to re-expose it.