vmselect: add -search.maxDeleteDuration to limit the duration of the /api/v1/admin/tsdb/delete_series call

Previously, it's reusing `-search.maxQueryDuration`.

app/vminsert/netstorage/netstorage.go

@@ -114,7 +114,7 @@ again:
 		rowsProcessed, err := rerouteRowsToReadyStorageNodes(snb, sn, buf)
 		rows -= rowsProcessed
 		if err != nil {
-			return fmt.Errorf("%d rows dropped because the current vsmtorage is unavailable and %w", rows, err)
+			return fmt.Errorf("%d rows dropped because the current vmstorage is unavailable and %w", rows, err)
 		}
 		return nil
 	}

app/vmselect/prometheus/prometheus.go

@@ -507,6 +507,8 @@ func DeleteHandler(startTime time.Time, at *auth.Token, r *http.Request) error {
 	if err != nil {
 		return err
 	}
+	cp.deadline = searchutils.GetDeadlineForDelete(r, startTime)
+	
 	if !cp.IsDefaultTimeRange() {
 		return fmt.Errorf("start=%d and end=%d args aren't supported. Remove these args from the query in order to delete all the matching metrics", cp.start, cp.end)
 	}

app/vmselect/searchutils/searchutils.go

@@ -15,6 +15,7 @@ import (
 
 var (
 	maxExportDuration        = flag.Duration("search.maxExportDuration", time.Hour*24*30, "The maximum duration for /api/v1/export call")
+	maxDeleteDuration        = flag.Duration("search.maxDeleteDuration", time.Minute*5, "The maximum duration for /api/v1/delete call")
 	maxQueryDuration         = flag.Duration("search.maxQueryDuration", time.Second*30, "The maximum duration for query execution. It can be overridden to a smaller value on a per-query basis via 'timeout' query arg")
 	maxStatusRequestDuration = flag.Duration("search.maxStatusRequestDuration", time.Minute*5, "The maximum duration for /api/v1/status/* requests")
 	maxLabelsAPIDuration     = flag.Duration("search.maxLabelsAPIDuration", time.Second*5, "The maximum duration for /api/v1/labels, /api/v1/label/.../values and /api/v1/series requests. "+
@@ -52,6 +53,12 @@ func GetDeadlineForExport(r *http.Request, startTime time.Time) Deadline {
 	return getDeadlineWithMaxDuration(r, startTime, dMax, "-search.maxExportDuration")
 }
 
+// GetDeadlineForDelete returns deadline for the given request to /api/v1/delete.
+func GetDeadlineForDelete(r *http.Request, startTime time.Time) Deadline {
+	dMax := maxDeleteDuration.Milliseconds()
+	return getDeadlineWithMaxDuration(r, startTime, dMax, "-search.maxDeleteDuration")
+}
+
 // GetDeadlineForLabelsAPI returns deadline for the given request to /api/v1/labels, /api/v1/label/.../values or /api/v1/series
 func GetDeadlineForLabelsAPI(r *http.Request, startTime time.Time) Deadline {
 	dMax := maxLabelsAPIDuration.Milliseconds()