Use the product token for the user agent in more locations (#7378)

plugins/outputs/http/http.go

@@ -193,7 +193,7 @@ func (h *HTTP) write(reqBody []byte) error {
 		req.SetBasicAuth(h.Username, h.Password)
 	}
 
-	req.Header.Set("User-Agent", "Telegraf/"+internal.Version())
+	req.Header.Set("User-Agent", internal.ProductToken())
 	req.Header.Set("Content-Type", defaultContentType)
 	if h.ContentEncoding == "gzip" {
 		req.Header.Set("Content-Encoding", "gzip")

plugins/outputs/http/http_test.go

@@ -431,11 +431,9 @@ func TestDefaultUserAgent(t *testing.T) {
 	u, err := url.Parse(fmt.Sprintf("http://%s", ts.Listener.Addr().String()))
 	require.NoError(t, err)
 
-	internal.SetVersion("1.2.3")
-
 	t.Run("default-user-agent", func(t *testing.T) {
 		ts.Config.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			require.Equal(t, "Telegraf/1.2.3", r.Header.Get("User-Agent"))
+			require.Equal(t, internal.ProductToken(), r.Header.Get("User-Agent"))
 			w.WriteHeader(http.StatusOK)
 		})