Update alert thresholds for rummager checks
Update alert thresholds for rummager checks

This adjusts the index alert thresholds based
on data for average weekly change.

Warning: 4 x Avg
Critical: 20 x Avg (5 x Warning)
alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet