Remove PagerDuty trigger for AWS Elasticache Redis
Remove PagerDuty trigger for AWS Elasticache Redis

- These alerts have been configured analogous to prior VM alerts, as
Redis is now hosted in AWS Elasticache, there is nothing for GOV.UK to
action.

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