MM-62288 - add e2e to RHS focus functionality (#29655)

* MM-62288 - add e2e to RHS focus functionality

* remove describe only

* Use existence check before closing RHS

* modify close rhs function to not fail when rhs is not opened

* avoid body to not get found

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/channels/src/components/sidebar_right/sidebar_right.tsx

@@ -157,7 +157,7 @@ export default class SidebarRight extends React.PureComponent<Props, State> {
 
         if (this.props.isOpen && (contentChanged || (!wasOpen && isOpen))) {
             this.previousActiveElement = document.activeElement as HTMLElement;
-            requestAnimationFrame(() => {
+            setTimeout(() => {
                 if (this.sidebarRight.current) {
                     document.dispatchEvent(
                         new CustomEvent<A11yFocusEventDetail>(A11yCustomEventTypes.FOCUS, {
@@ -168,14 +168,14 @@ export default class SidebarRight extends React.PureComponent<Props, State> {
                         }),
                     );
                 }
-            });
+            }, 0);
         } else if (!this.props.isOpen && wasOpen) {
             // RHS just was closed, restore focus to the previous element had it
             // this will have to change for upcoming work specially for search and probalby plugins
             if (a11yController.originElement) {
                 a11yController.restoreOriginFocus();
             } else {
-                requestAnimationFrame(() => {
+                setTimeout(() => {
                     if (this.previousActiveElement) {
                         document.dispatchEvent(
                             new CustomEvent<A11yFocusEventDetail>(A11yCustomEventTypes.FOCUS, {
@@ -187,7 +187,7 @@ export default class SidebarRight extends React.PureComponent<Props, State> {
                         );
                         this.previousActiveElement = null;
                     }
-                });
+                }, 0);
             }
         }
     }