message: Graphs: Fix Prometheus `query_range` graphs in older browsers
  Fixes
  Calling the `URLSearchParams` constructor with a sequence only started
  to be supported by browsers fairly recently. Although we don't strictly
  support these older browsers, the fix is simple.
diff: @@ -10,16 +10,19 @@ export enum PrometheusEndpoint {
  // Range vector queries require end, start, and step search params
  const getRangeVectorSearchParams = (timespan: number, endTime: number = Date.now(), samples: number = 60): URLSearchParams => {
  - const init = timespan ? [
  - [ 'end', `${endTime / 1000}` ],
  - [ 'start', `${(endTime - timespan) / 1000}` ],
  - [ 'step', `${timespan / samples / 1000}` ],
  - ] : [];
  - return new URLSearchParams(init);
  + const params = new URLSearchParams();
  + if (timespan) {
  + params.set('start', String((endTime - timespan) / 1000));
  + params.set('end', String(endTime / 1000));
  + params.set('step', String((timespan / samples) / 1000));
  + }
  + return params;
  };
  const getSearchParams = ({endpoint, endTime, timespan, samples, ...params}: PrometheusURLProps): URLSearchParams => {
  - const searchParams = endpoint === PrometheusEndpoint.QUERY_RANGE ? getRangeVectorSearchParams(timespan, endTime, samples) : new URLSearchParams();
  + const searchParams = endpoint === PrometheusEndpoint.QUERY_RANGE
  + ? getRangeVectorSearchParams(timespan, endTime, samples)
  + : new URLSearchParams();
  _.each(params, (value, key) => value && searchParams.append(key, value.toString()));
  return searchParams;
  };
  