Fixed Add Channel_test_cases (#22768)

* Fixed Add Channel_test_cases

* fixed more test cases

* fixed lint

e2e-tests/cypress/tests/integration/channels/enterprise/ldap/ldap_guest_spec.js

@@ -159,7 +159,7 @@ describe('LDAP guest', () => {
         // # Create team if no membership
         cy.skipOrCreateTeam(testSettings, getRandomId()).then(() => {
             // * Verify user is a member
-            cy.findByRole('button', {name: 'Add Channel Dropdown'}).should('exist');
+            cy.uiGetLHSAddChannelButton().should('exist');
 
             // # Demote the user
             demoteUserToGuest(user2Data);
@@ -173,7 +173,7 @@ describe('LDAP guest', () => {
                 cy.uiAddDirectMessage().should('exist');
 
                 // * Check the user is a guest
-                cy.findByRole('button', {name: 'Add Channel Dropdown'}).should('not.exist');
+                cy.uiGetLHSAddChannelButton().should('not.exist');
             });
         });
     });