satellite/satellitedb: remove monkit trace from convertDBNode

In jaeger, it shows that this function gets called repetitively in
a single request. Most of the time, it's less than 1ms. Therefore, it
doesn't add much value in our trace but create noises.

Change-Id: I20234f36bbcf0fc22f91e5e1a5634c0cad577ed0

satellite/satellitedb/overlaycache.go

@@ -887,7 +887,6 @@ func (cache *overlaycache) GetOfflineNodesLimited(ctx context.Context, limit int
 }
 
 func convertDBNode(ctx context.Context, info *dbx.Node) (_ *overlay.NodeDossier, err error) {
-	defer mon.Task()(&ctx)(&err)
 	if info == nil {
 		return nil, Error.New("missing info")
 	}