Fix flaky test src/room/composer/Banner/Banner.stories.tsx > With Avatar Image (#33275)

* Fix flaky test `src/room/composer/Banner/Banner.stories.tsx > With Avatar Image`

it was previously loading an external (slow) image which was random (!) by design

Fixes https://github.com/element-hq/element-web/issues/33273

* Fix styling

* Iterate

* Update snapshot

apps/web/test/unit-tests/components/structures/__snapshots__/RoomView-test.tsx.snap

@@ -213,12 +213,12 @@ exports[`RoomView for a local room in state ERROR should match the snapshot 1`]
       </div>
       <div
         aria-labelledby="_r_1c3_"
-        class="_banner_193k4_8"
+        class="_banner_n7ud0_8"
         data-type="critical"
         role="status"
       >
         <div
-          class="_icon_193k4_50"
+          class="_icon_n7ud0_50"
         >
           <svg
             fill="currentColor"
@@ -234,7 +234,7 @@ exports[`RoomView for a local room in state ERROR should match the snapshot 1`]
           </svg>
         </div>
         <div
-          class="_content_193k4_38"
+          class="_content_n7ud0_38"
         >
           <p
             class="_typography_6v6n8_153 _font-body-md-medium_6v6n8_60 _title_1xryk_24"
@@ -244,7 +244,7 @@ exports[`RoomView for a local room in state ERROR should match the snapshot 1`]
           </p>
         </div>
         <div
-          class="_actions_193k4_60"
+          class="_actions_n7ud0_61"
         >
           <button
             class="_button_13vu4_8 _primaryAction_1xryk_20 _has-icon_13vu4_60"