[Glitch] Fix loading indicator inconsistency

Port 3cecf3e5b9 to glitch-soc

app/javascript/flavours/glitch/features/notifications/index.js

@@ -187,6 +187,7 @@ export default class Notifications extends React.PureComponent {
         scrollKey={`notifications-${columnId}`}
         trackScroll={!pinned}
         isLoading={isLoading}
+        showLoading={isLoading && notifications.size === 0}
         hasMore={hasMore}
         emptyMessage={emptyMessage}
         onLoadMore={this.handleLoadOlder}