We don't want large numbers in Production to start overlapping other columns
in the tables when they have less space available, and putting these messages
at the top of the page under the h1 means that we don't need an extra column
on the page yet.
When we make the numbers on this page more filterable the date range will be
one of the options to change, so it makes sense to move it to the side now
instead of leaving it above the big numbers.
This page currently includes all notifications for all services, including
those sent using a test key. Stats on all other pages exclude test key usage,
though, which can lead to confusion for admins comparing numbers between
pages. Adding the option to toggle between including and excluding test key
usage on the platform admin page gives context for this difference, and allows
admins to see live usage of the platform as well as load associated with test
key usage.
