Purges a field instance record from the database.
This function assumes all data for the instance has already been purged and should only be called by field_purge_batch().
$instance: The instance record to purge.
function field_purge_instance($instance) {
// Notify the storage engine.
$field = field_info_field_by_id($instance['field_id']);
module_invoke($field['storage']['module'], 'field_storage_purge_instance', $instance);
$state = Drupal::state();
$deleted_instances = $state
->get('field.instance.deleted');
unset($deleted_instances[$instance['uuid']]);
$state
->set('field.instance.deleted', $deleted_instances);
// Clear the cache.
field_info_cache_clear();
// Invoke external hooks after the cache is cleared for API consistency.
module_invoke_all('field_purge_instance', $instance);
}