Fixes #19034 - add tasks for clearing expired notifications

fixes #19131 - upgrade minitest to latest 5.x

- override minitest's `_` expectation method with the gettext method
- rename `location` let helper, conflicted with a minitest method name
- fix `assert_equal nil, [..]` deprecation warnings, prefer `assert nil`...

fixes #18940 - adds caching to notification api calls.

this implementation reduce the notification fetching time on
my production system from avg response times of 80ms to 20ms,
and siginficantly reducing server load (db, cpu etc)

it also removes total counts from the implementation, as that was not...

Fixes #18952 - fix destroy of host without owner

The notifications failure caused the host not being deleted.
I don't think the notifications should interfere with the core
functionality of the objects.

fixes #18681 - moves polymorphic subject into notification object

also adds host build, destroyed and missing owner UI notifications