Fix alignment regression error with area lists

When we changed the layout for each alert on the
current/past/rejected alerts pages to use flexbox,
we added a fallback for older browsers that set
text-align: justify on the container:

https://github.com/alphagov/notifications-admin/pull/4171

This has led to items in the list of areas an
alert will be sent to being laid out as justified
content when they were left-aligned.

These changes set the correct alignment.

app/assets/stylesheets/views/dashboard.scss

@@ -55,6 +55,7 @@
     & > :first-child,
     & > .area-list {
       width: 100%;
+      text-align: left;
     }
 
     & > .file-list-hint-large,