Increase warning threshold for nginx high active connections
Increase warning threshold for nginx high active connections

The number of active connection is regularly above the 500 warning
threshold. Increasing to 650 as this is still 350 below the critical
threshold.

This cover the level we are regularly seeing.

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