Clear floating elements before the panels in the worker activity view

https://redmine.teklia.com/issues/10672

The buttons in the process worker activity stats view use float: right. Since the Bulma 1 update, some margins and button sizes have changed and the buttons are now overlapping a little with the panels for each worker, so the title bar for the first panel gets resized. Either clear: both should be applied somewhere before the panels, or float should be avoided entirely.