cypress: handle overflow menu in impress/slide_operations_spec.js

after adding button to insert canvas page, insert slides group turns
into overflow menu

Signed-off-by: Mohit Marathe <[email protected]>
Change-Id: I6fc11d23f2dba286977950b602a53eec3f10d316

Author: mohit-marathe

cypress_test/integration_tests/desktop/impress/slide_operations_spec.js

@@ -62,6 +62,7 @@ describe(['tagdesktop', 'tagnextcloud', 'tagproxy'], 'Slide operations', functio
 		desktopHelper.insertComment();
 		cy.cGet('[id^=annotation-content-area-]').should('include.text', 'some text0');
 		cy.cGet('#Insert-tab-label').click();
+		cy.cGet('#overflow-button-insert-slide').click();
 		cy.cGet('#insert-duplicate-slide').click();
 
 		impressHelper.assertNumberOfSlidePreviews(2);