Add new disc to api_mongo machines
Add new disc to api_mongo machines

See https://github.gds/gds/govuk-provisioning/pull/295 for justification.
Adds /dev/sdd1 to the mongodb-backup LVM group.

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