Add env vars for signon Splunk event log streaming
Add env vars for signon Splunk event log streaming

This commit adds the required env vars to allow the signon app to stream its event logs to Splunk for analysis.

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