[MM-61637]: Add accessible name to the expand RHS button in RHS header (#29783)

* [MA-48]: Add aria-label

* [MA-48]: Update snapshots

* [MA-48]: Fix E2E tests

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

@@ -19,7 +19,7 @@ Cypress.Commands.add('uiCloseRHS', () => {
 });
 
 Cypress.Commands.add('uiExpandRHS', () => {
-    cy.findByLabelText('Expand').click();
+    cy.findByLabelText('Expand Sidebar Icon').click();
 });
 
 Cypress.Commands.add('isExpanded', {prevSubject: true}, (subject) => {