Annual shipping features nav links will break playwright tests twice a year

[jrobbins]

We now have date-based logic that changes the navigation links in chromedash-drawer.ts twice a year. That will break our screenshot matching playwright tests twice a year. We could redact part of the image to exclude that part from image comparison, but that won't help with this change because it adds a row to the menu, thus affecting the layout of all the items lower in the menu.

[jrobbins]

I think the solution is to make the app behave a bit differently while being tested than what it does when run in prod. We do that already to add the sign-in-as-example button. In this case, it would display Shipping YEAR rather than show any year number, and it would always display one such link rather than two.