CI Secrets vault usage instrumentation with Snowplow

What does this MR do and why?

This MR adds Snowplow instrumentation to track the usage of secrets: (vault integration) in the CI pipeline.

The instrumentation works by tracking the event when a pipeline Build job is created with secrets defined. This Snowplow metric is a mirror of the existing Service Ping RedisHLL metric with key_path: redis_hll_counters.ci_secrets_management.i_ci_secrets_management_vault_build_created_monthly

This MR resolves Instrument tracking for Secrets usage using Sno... (#388838 - closed). A similar MR for id_tokens was previously merged--it implements the same tracking method.

How to set up and validate locally

1. secrets: is a Premium feature so ensure your local instance is licensed.
2. Configure your GDK to run Snowplow Micro.
3. Go to http://gdk.test:9091/micro/good to observe the events being tracked.
4. Go to your Project's CI/CD Editor and update the contents with the following.

job_with_secrets:
  secrets:
    MY_SECRET:
      vault: production/db/password
  script:
    - echo 'test'

4. Commit the changes and run the pipeline. Note that the job will fail (unless you have a valid vault set up locally). Refresh http://gdk.test:9091/micro/good and observe that an event appears with se_action: value create_secrets_vault.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #388838 (closed)