Use email-alert-api JSON healthcheck
Use email-alert-api JSON healthcheck

Note: This is the same change as b7c7f6d from gds/puppet#2311 that was
erroneously merged too early by me.

This was added recently to monitor queue size and age. Use those checks
in Nagios.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet