Empty geocoding results do not respect the override checkbox state.

Problem/Motivation

After #3002517: Geofield remains empty when I choose "Geocode from another field" → the behaviour of geocoder_field_attach_presave() changed. Apart from the intended purpose of this issue, the geofield is now set to an empty value after (unsuccessful) geocoding, without taking the status of the override checkbox ($entity->geocoder_overridden) into account. This checkbox is only considered in the code path for successful geocoding.

Proposed resolution

In the current state (after #3002517: Geofield remains empty when I choose "Geocode from another field" → ), different behaviour for if ($geocoded_value = geocoder_widget_get_field_value($entity_type, $instance, $entity)) makes no sense. Remove this if/else clause and always run the code on the if block.