Fix missing URL for Deploy_App_Downstream job
Fix missing URL for Deploy_App_Downstream job

Previously this used to be hard-coded in the 'integration_deploy'
job, because it only ran on CI.

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