feat(UI): simplify code (#2847)

Avoid branching on the same condition and remove unneeded showToolbar call on
filmstrip only mode.

modules/UI/UI.js

     VideoLayout.resizeVideoArea(true, true);
 
     sharedVideoManager = new SharedVideoManager(eventEmitter);
-    // eslint-disable-next-line no-negated-condition
-    if (!interfaceConfig.filmStripOnly) {
-        // Initialise the recording module.
-        if (config.enableRecording) {
-            Recording.init(eventEmitter, config.recordingType);
-        }
 
-        // Initialize side panels
-        SidePanels.init(eventEmitter);
-    } else {
+    if (interfaceConfig.filmStripOnly) {
         $('body').addClass('filmstrip-only');
-        UI.showToolbar();
         Filmstrip.setFilmstripOnly();
         APP.store.dispatch(setNotificationsEnabled(false));
-    }
+    } else {
+        // Initialise the recording module.
+        config.enableRecording
+            && Recording.init(eventEmitter, config.recordingType);
 
-    if (interfaceConfig.VERTICAL_FILMSTRIP) {
-        $('body').addClass('vertical-filmstrip');
-    }
+        // Initialize side panels
+        SidePanels.init(eventEmitter);
 
-    // TODO: remove this class once the old toolbar has been removed. This class
-    // is set so that any CSS changes needed to adjust elements outside of the
-    // new toolbar can be scoped to just the app with the new toolbar enabled.
-    if (!interfaceConfig.filmStripOnly) {
+        // TODO: remove this class once the old toolbar has been removed. This
+        // class is set so that any CSS changes needed to adjust elements
+        // outside of the new toolbar can be scoped to just the app with the new
+        // toolbar enabled.
         $('body').addClass('use-new-toolbox');
     }
 
+    interfaceConfig.VERTICAL_FILMSTRIP
+        && $('body').addClass('vertical-filmstrip');
+
     document.title = interfaceConfig.APP_NAME;
 };