smbd: only increment lease epoch if a lease was granted

From MS-SMB2 3.3.5.9.11 "Handling the SMB2_CREATE_REQUEST_LEASE_V2 Create
Context":

  If the object store succeeds this request, Lease.LeaseState MUST be set to the
  new caching state.  The server MUST increment Lease.Epoch by 1.

try_lease_upgrade() already has the same logic when checking for a possible
upgrade of an exisiting lease.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15933

Signed-off-by: Ralph Boehme <[email protected]>
Reviewed-by: Volker Lendecke <[email protected]>

Autobuild-User(master): Volker Lendecke <[email protected]>
Autobuild-Date(master): Fri Oct 10 17:02:26 UTC 2025 on atb-devel-224

(cherry picked from commit 9f45eae)

Autobuild-User(v4-23-test): Jule Anger <[email protected]>
Autobuild-Date(v4-23-test): Wed Oct 15 15:10:19 UTC 2025 on atb-devel-224

Author: slowfranklin

selftest/knownfail.d/samba3.smb2.lease

@@ -2056,7 +2056,10 @@ static NTSTATUS grant_new_fsp_lease(struct files_struct *fsp,
 	fsp->lease->lease.parent_lease_key = lease->parent_lease_key;
 	fsp->lease->lease.lease_flags = lease->lease_flags;
 	fsp->lease->lease.lease_state = granted;
-	fsp->lease->lease.lease_epoch = lease->lease_epoch + 1;
+	fsp->lease->lease.lease_epoch = lease->lease_epoch;
+	if (granted != 0) {
+		fsp->lease->lease.lease_epoch++;
+	}
 
 	status = leases_db_add(client_guid,
 			       &lease->lease_key,