integration test for deletion of series (grafana#2946)

* integration test for deletion of series

Signed-off-by: Sandeep Sukhani <sandeep.d.sukhani@gmail.com>

* update changelog

Signed-off-by: Sandeep Sukhani <sandeep.d.sukhani@gmail.com>

* Reuse existing timeout

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Removed Println()

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Assert on Purger metrics too

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Removed time.Sleep() from delete series integration test

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Moved CHANGELOG entry

Signed-off-by: Marco Pracucci <marco@pracucci.com>

Co-authored-by: Marco Pracucci <marco@pracucci.com>

purger/request_handler.go

@@ -113,6 +113,7 @@ func (dm *DeleteRequestHandler) AddDeleteRequestHandler(w http.ResponseWriter, r
 	}
 
 	dm.metrics.deleteRequestsReceivedTotal.WithLabelValues(userID).Inc()
+	w.WriteHeader(http.StatusNoContent)
 }
 
 // GetAllDeleteRequestsHandler handles get all delete requests
@@ -177,5 +178,5 @@ func (dm *DeleteRequestHandler) CancelDeleteRequestHandler(w http.ResponseWriter
 		return
 	}
 
-	w.WriteHeader(http.StatusOK)
+	w.WriteHeader(http.StatusNoContent)
 }