fix(ui): enable observer batching in mobx

https://github.com/mobxjs/mobx-react-lite/#observer-batching

ui/.storybook/config.js

@@ -8,6 +8,8 @@ import {
 
 import createPercyAddon from "@percy-io/percy-storybook";
 
+import "mobx-react-lite/batchingForReactDom";
+
 import { advanceTo } from "jest-date-mock";
 
 import { ThemeContext } from "Components/Theme";

ui/src/index.tsx

@@ -9,6 +9,8 @@ import ReactDOM from "react-dom";
 
 import Moment from "react-moment";
 
+import "mobx-react-lite/batchingForReactDom";
+
 import {
   SettingsElement,
   SetupSentry,

ui/src/setupTests.js

@@ -3,6 +3,8 @@ import Adapter from "enzyme-adapter-react-16";
 
 import { FetchRetryConfig } from "Common/Fetch";
 
+import "mobx-react-lite/batchingForReactDom";
+
 // https://github.com/airbnb/enzyme
 Enzyme.configure({ adapter: new Adapter() });