message: Monitoring: Redirect Prometheus UI format URLs to query browser page
  Alert notification messages sent by Alertmanager contain links for
  inspecting the relevant PromQL query in the UI. However, these links
  have the Prometheus UI's URL format. This adds a route for redirecting
  those URLs to our Metrics page.
diff: @@ -1797,10 +1797,19 @@ const PollerPages = () => {
  );
  };
  +// Handles links that have the Prometheus UI's URL format (expected for links in alerts sent by
  +// Alertmanager). The Prometheus UI specifies the PromQL query with the GET param `g0.expr`, so we
  +// use that if it exists. Otherwise, just go to the query browser page with no query.
  +const PrometheusUIRedirect = () => {
  + const params = getURLSearchParams();
  + return <Redirect to={`/monitoring/query-browser?query0=${params['g0.expr'] || ''}`} />;
  +};
  +
  export const MonitoringUI = () => (
  <Switch>
  <Redirect from="/monitoring" exact to="/monitoring/alerts" />
  <Route path="/monitoring/dashboards/:board?" exact component={MonitoringDashboardsPage} />
  + <Route path="/monitoring/graph" exact component={PrometheusUIRedirect} />
  <Route path="/monitoring/query-browser" exact component={QueryBrowserPage} />
  <Route path="/monitoring/silences/~new" exact component={CreateSilence} />
  <Route path="/monitoring/targets" component={TargetsUI} />
  