fix: use a Box link that will work when MyUW is unavailable

The problem with linking to the MyUW details page, is that in the circumstances where the outage page is showing, that MyUW details page probably won't render. So instead link out to Box, which is what the app directory details page would have done anyway.

myuw-root-webapp/src/main/webapp/500.html

@@ -41,7 +41,7 @@
                 <h4>UW-Madison Top Resources</h4>
                 <h5>Apps</h5>
                 <ul role="menu" aria-labelledby="service-links__uw-madison">
-                  <li role="menuitem"><a href="https://my.wisc.edu/web/apps/details/box">Box</a></li>
+                  <li role="menuitem"><a href="https://uwmadison.box.com/">Box</a></li>
                   <li role="menuitem"><a href="https://outlook.office.com/calendar/view/month">Calendar (Outlook)</a></li>
                   <li role="menuitem"><a href="https://canvas.wisc.edu/">Canvas</a></li>
                   <li role="menuitem"><a href="https://doodle.com/en/">Doodle</a></li>