Prometheus: Fix passing query timeout to upstream queries (#95104)

* remove queryTimeout from constructor

* use queryTimeout for range and instant queries

* remove comment

* remove default query timeout

* fix linting

pkg/promlib/client/client.go

@@ -24,13 +24,14 @@ type doer interface {
 // objects, we have to go through them and then serialize again into DataFrame which isn't very efficient. Using custom
 // client we can parse response directly into DataFrame.
 type Client struct {
-	doer    doer
-	method  string
-	baseUrl string
+	doer         doer
+	method       string
+	baseUrl      string
+	queryTimeout string
 }
 
-func NewClient(d doer, method, baseUrl string) *Client {
-	return &Client{doer: d, method: method, baseUrl: baseUrl}
+func NewClient(d doer, method, baseUrl, queryTimeout string) *Client {
+	return &Client{doer: d, method: method, baseUrl: baseUrl, queryTimeout: queryTimeout}
 }
 
 func (c *Client) QueryRange(ctx context.Context, q *models.Query) (*http.Response, error) {
@@ -41,6 +42,9 @@ func (c *Client) QueryRange(ctx context.Context, q *models.Query) (*http.Respons
 		"end":   formatTime(tr.End),
 		"step":  strconv.FormatFloat(tr.Step.Seconds(), 'f', -1, 64),
 	}
+	if c.queryTimeout != "" {
+		qv["timeout"] = c.queryTimeout
+	}
 
 	req, err := c.createQueryRequest(ctx, "api/v1/query_range", qv)
 	if err != nil {
@@ -58,6 +62,9 @@ func (c *Client) QueryInstant(ctx context.Context, q *models.Query) (*http.Respo
 	// Instead of aligning we use time point directly.
 	// https://prometheus.io/docs/prometheus/latest/querying/api/#instant-queries
 	qv := map[string]string{"query": q.Expr, "time": formatTime(q.End)}
+	if c.queryTimeout != "" {
+		qv["timeout"] = c.queryTimeout
+	}
 	req, err := c.createQueryRequest(ctx, "api/v1/query", qv)
 	if err != nil {
 		return nil, err