Reset batchSize in timer condition too

Signed-off-by: Eugen Biegler <nupagadi@posteo.de>

pkg/promtail/client.go

@@ -128,6 +128,7 @@ func (c *Client) run() {
 				if err := c.send(batch); err != nil {
 					level.Error(c.logger).Log("msg", "error sending batch", "error", err)
 				}
+				batchSize = 0
 				batch = map[model.Fingerprint]*logproto.Stream{}
 			}
 		}