EES-5742 Fix UI tests

[mmyoungman]

This PR changes the headless argument we use when opening google-chrome in the UI tests to not use "old".

We did this because we started seeing failures like this:

2025-01-28T10:26:13.8418368Z UI Tests.Glossary Page                                                        
2025-01-28T10:26:13.8418684Z ==============================================================================
2025-01-28T10:26:13.8418983Z Navigate to glossary page                                             | FAIL |
2025-01-28T10:26:13.8419220Z Parent suite setup failed:
2025-01-28T10:26:13.8419591Z SessionNotCreatedException: Message: session not created: probably user data directory is already in use, please specify a unique value for --user-data-dir argument, or don't use --user-data-dir

It seems like newer version of google-chrome and chromedriver have broken "headless=old".