POST request to /api/v4/container_registry_event/events should not be subject to Rack Attack

We observed that in #327299 (comment 548957055), the enabling of registry notification events with Geo (gitlab-com/gl-infra/k8s-workloads/gitlab-com!777 (merged)) caused an uptick in Rack Attack throttling to unauthenticated endpoints:

image

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This had an unintended side effect of throttling remote YML fetches as well.

We should probably:

  1. Treat these POST requests as authenticated
  2. Ensure Rack Attack doesn't throttle them

/cc: @vsizov, @10io, @skarbek

Edited by Stan Hu