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

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

e2e-tests/cypress/tests/support/ui/sidebar_right.js

@@ -10,7 +10,12 @@ Cypress.Commands.add('uiGetRHS', (options = {visible: true}) => {
 });
 
 Cypress.Commands.add('uiCloseRHS', () => {
-    cy.findByLabelText('Close Sidebar Icon').click();
+    cy.document().then((doc) => {
+        const closeButton = doc.querySelector('[aria-label="Close Sidebar Icon"]');
+        if (closeButton) {
+            closeButton.click();
+        }
+    });
 });
 
 Cypress.Commands.add('uiExpandRHS', () => {