Default email-campaign-api redis host
Default email-campaign-api redis host

This is going to be set to this value in almost all environments, so
it makes sense to set the default in the class.

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