Make API key locator work for old + new key format
Make API key locator work for old + new key format

The API keys page will show:

- new format

Then
- service ID
- API key (old format)

So the thing that the functional tests needs will always be the last one
on the page.

This should mean we can merge
https://github.com/alphagov/notifications-admin/pull/968
without breaking anything.

alphagov/notifications-functional-tests,alphagov/notifications-functional-tests