Support feature worker declaration from gitlab.teklia.com

Closes #1883 (closed)

• Requires tests

arkindex/process/management/commands/update_system_workers.py

@@ -147,8 +147,6 @@ class Command(BaseCommand):
 
         self.stdout.write("Creating new worker version")
         max_version = worker.versions.aggregate(max_version=Max("version"))["max_version"] or 0
-        if configuration.get("docker") is None and docker_command:
-            configuration["docker"] = {"command": docker_command}
         worker_version = worker.versions.create(
             docker_image_iid=docker_image,
             feature=feature,
@@ -259,4 +257,7 @@ class Command(BaseCommand):
             if worker is not None:
                 self.update_feature_from_worker(feature, **worker)
             else:
-                self.update_feature(feature, **feature_config)
+                configuration = {}
+                if (command := feature_config["command"]):
+                    configuration["docker"] = {"command": command}
+                self.update_feature(feature, **feature_config, configuration=configuration)