Update threat insights endpoint urgency for new error budget opt in

Stage groups are moving from the original error budgets framework to an improved one that allows for some customization of apdex thresholds. See Error Budgets: Using custom target durations fo... (gitlab-com/gl-infra/scalability#1451 - closed)

The two versions of error budgets used different default thresholds (5 seconds vs. 1 seconds) which means teams need to explicitly update the thresholds for all endpoints to maintain their current error budget thresholds and avoid negatively impacting their error budgets.

This MR updates all endpoints for the secure:threat insights group to maintain the current 5 second threshold. Doing this enables teams to opt into the new framework prior to doing a full analysis of their endpoints to determine how a change in apdex threshold will impact their error budget.