Add format to product_group field in metrics definition and update incorrect values

Summary

Add format group::<group name> to Service Ping metrics definitions

Update inconsistent values

Why

These values are used in queries and we expect to be consistent with the way we define the values.

Resources

• Metrics dictionary guide https://docs.gitlab.com/ee/development/service_ping/metrics_dictionary.html
• Metrics definition JSON schema https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/metrics/schema.json

Testing

Update relevant unit tests if any.