FIX: destroys instance when hiding date popover (#16623)

This fix attempts to fix an issue where the preview was not updated after changing timezone. Changing time would work as it would recreate the date DOM element and as a result, reset the popper.

plugins/discourse-local-dates/assets/javascripts/initializers/discourse-local-dates.js

@@ -268,6 +268,9 @@ export default {
       allowHTML: true,
       interactive: true,
       appendTo: "parent",
+      onHidden: (instance) => {
+        instance.destroy();
+      },
     });
   },