[#1094] services/object: remove some FIXME comments

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/services/object/head/remote.go

@@ -32,6 +32,8 @@ type RemoteHeadPrm struct {
 	node *netmap.NodeInfo
 }
 
+const remoteOpTTL = 1
+
 var ErrNotFound = errors.New("object header not found")
 
 // NewRemoteHeader creates, initializes and returns new RemoteHeader instance.
@@ -85,7 +87,7 @@ func (h *RemoteHeader) Head(ctx context.Context, prm *RemoteHeadPrm) (*object.Ob
 	headPrm.SetClient(c)
 	headPrm.SetPrivateKey(key)
 	headPrm.SetAddress(prm.commonHeadPrm.addr)
-	headPrm.SetTTL(1) // FIXME: use constant
+	headPrm.SetTTL(remoteOpTTL)
 
 	res, err := internalclient.HeadObject(headPrm)
 	if err != nil {

pkg/services/object/util/prm.go

@@ -8,6 +8,9 @@ import (
 	"github.com/nspcc-dev/neofs-sdk-go/token"
 )
 
+// maxLocalTTL is maximum TTL for an operation to be considered local.
+const maxLocalTTL = 1
+
 type CommonPrm struct {
 	local bool
 
@@ -103,7 +106,7 @@ func CommonPrmFromV2(req interface {
 	ttl := meta.GetTTL()
 
 	prm := &CommonPrm{
-		local: ttl <= 1, // FIXME: use constant
+		local: ttl <= maxLocalTTL,
 		xhdrs: make([]*sessionsdk.XHeader, 0, len(xHdrs)),
 		ttl:   ttl - 1, // decrease TTL for new requests
 	}