message: Monitoring: Prevent unnecessary polling on some pages
  There's no need for the Prometheus API and Alertmanager API polling to
  be running on the Query Browser page or the Create Silence page.
diff: @@ -993,7 +993,7 @@ const CreateSilence = () => {
  : <SilenceForm defaults={{matchers}} saveButtonText="Create" title="Silence Alert" />;
  };
  -export class MonitoringUI extends React.Component<null, null> {
  +class PollerPages extends React.Component<null, null> {
  componentDidMount() {
  const poll = (url: string, key: 'alerts' | 'silences', dataHandler: (data: any[]) => any): void => {
  store.dispatch(UIActions.monitoringLoading(key));
  @@ -1053,24 +1053,28 @@ export class MonitoringUI extends React.Component<null, null> {
  }
  componentWillUnmount() {
  - _.each(pollerTimeouts, t => clearTimeout(t));
  + _.each(pollerTimeouts, clearTimeout);
  }
  render() {
  return <Switch>
  - <Redirect from="/monitoring" exact to="/monitoring/alerts" />
  <Route path="/monitoring/alerts" exact component={AlertsPage} />
  <Route path="/monitoring/alerts/:ruleID" exact component={AlertsDetailsPage} />
  <Route path="/monitoring/alertrules/:id" exact component={AlertRulesDetailsPage} />
  <Route path="/monitoring/silences" exact component={SilencesPage} />
  - <Route path="/monitoring/silences/~new" exact component={CreateSilence} />
  <Route path="/monitoring/silences/:id" exact component={SilencesDetailsPage} />
  <Route path="/monitoring/silences/:id/edit" exact component={EditSilence} />
  - <Route path="/monitoring/query-browser" exact component={QueryBrowserPage} />
  </Switch>;
  }
  }
  +export const MonitoringUI = () => <Switch>
  + <Redirect from="/monitoring" exact to="/monitoring/alerts" />
  + <Route path="/monitoring/query-browser" exact component={QueryBrowserPage} />
  + <Route path="/monitoring/silences/~new" exact component={CreateSilence} />
  + <Route component={PollerPages} />
  +</Switch>;
  +
  type Silence = {
  comment: string;
  createdBy: string;
  