[#1458] object: Make patch not set key before target construction

* `SignRequestPrivateKey` field should be initialized either within
  `newUntrustedTarget` or within `newTrustedTarget`. Otherwise, all
  requests are signed by local node key that makes impossible to perform
  patch on non-container node.

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

pkg/services/object/patch/streamer.go

@@ -113,10 +113,9 @@ func (s *Streamer) init(ctx context.Context, req *objectV2.PatchRequest) error {
 	oV2.GetHeader().SetOwnerID(ownerID)
 
 	target, err := target.New(objectwriter.Params{
-		Config:                s.Config,
-		Common:                commonPrm,
-		Header:                objectSDK.NewFromV2(oV2),
-		SignRequestPrivateKey: s.localNodeKey,
+		Config: s.Config,
+		Common: commonPrm,
+		Header: objectSDK.NewFromV2(oV2),
 	})
 	if err != nil {
 		return fmt.Errorf("target creation: %w", err)