ejabberd: Backup and restore functional test fails occasionally

Ejabberd 'backup and restore' functional test fails occasionally:

../../.local/lib/python3.8/site-packages/pytest_bdd/scenario.py:166: in _execute_scenario                                                         
    _execute_step_function(request, scenario, step, step_func)                                                                                    
../../.local/lib/python3.8/site-packages/pytest_bdd/scenario.py:115: in _execute_step_function                                                    
    step_func(**kwargs)                                                                                                                           
plinth/modules/ejabberd/tests/test_functional.py:20: in ejabberd_delete_contact                                                                   
    _jsxc_delete_contact(session_browser)                                                                                                         
plinth/modules/ejabberd/tests/test_functional.py:88: in _jsxc_delete_contact                                                                      
    browser.find_by_css('div.jsxc_more').first.click()                                                                                            
../../.local/lib/python3.8/site-packages/splinter/element_list.py:57: in first                                                                    
    return self[0]                                                                                                                                
...                                                                                                                                                                                                                  
E           splinter.exceptions.ElementDoesNotExist: no elements could be found with css "div.jsxc_more"

I think it is not related to the recent changes in security headers because it was failing sometimes even before.