pintracker: clean exit during recover

Shutting down the cluster while a recover operation is ongoing resulted in
each remaining pin in the recover loop producing an error in the logs, as the
loop kept going even though compontents were already shutdown.

With 8 million items, this meant a lot of log messages, and a shutdown delay
that forced the killing of the process in most cases.

The recover loop now exits when the component's context is cancelled.

pintracker/stateless/stateless.go

@@ -424,11 +424,19 @@ func (spt *Tracker) RecoverAll(ctx context.Context) ([]*api.PinInfo, error) {
 	statuses := spt.StatusAll(ctx, api.TrackerStatusUndefined)
 	resp := make([]*api.PinInfo, 0)
 	for _, st := range statuses {
-		r, err := spt.recoverWithPinInfo(ctx, st)
-		if err != nil {
-			return resp, err
+		// Break out if we shutdown. We might be going through
+		// a very long list of statuses.
+		select {
+		case <-spt.ctx.Done():
+			return nil, spt.ctx.Err()
+		default:
+			r, err := spt.recoverWithPinInfo(ctx, st)
+			if err != nil {
+				return resp, err
+			}
+			resp = append(resp, r)
 		}
-		resp = append(resp, r)
+
 	}
 	return resp, nil
 }