internal/target: delete support for PulpOSTree target

It turned out that the target was never adopted by the service, thus it
is being removed as part of the upload code consolidation.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

internal/target/target.go

@@ -93,8 +93,6 @@ func (target *Target) UnmarshalJSON(data []byte) error {
 		options = new(ContainerTargetOptions)
 	case TargetNameWorkerServer:
 		options = new(WorkerServerTargetOptions)
-	case TargetNamePulpOSTree:
-		options = new(PulpOSTreeTargetOptions)
 	default:
 		return fmt.Errorf("unexpected target name: %s", rawTarget.Name)
 	}
@@ -280,10 +278,6 @@ func (target Target) MarshalJSON() ([]byte, error) {
 			// the incompatible change.
 			rawOptions, err = json.Marshal(target.Options)
 
-		case *PulpOSTreeTargetOptions:
-			// added after incompatibility change
-			rawOptions, err = json.Marshal(target.Options)
-
 		default:
 			return nil, fmt.Errorf("unexpected target options type: %t", t)
 		}