Fix missing use of feature flag on Collections
Fix missing use of feature flag on Collections

The env var was set previously in puppet, but we didn't configure for it to be available to the app. [1]

1 https://github.com/alphagov/govuk-puppet/pull/11781

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