Fix package event metrics aggregation

What does this MR do?

Currently, the package events unique counters are aggregated under categories names like #{package_type}_packages. This puts user events in the same bucket as deploy token events, causing the two to be counted together which doesn't make sense.

This MR introduces:

1. Change the unique counter aggregation category to either user_packages or deploy_token packages, so that events fall into the proper category.
2. Simplify the unique events to include only package type, since we (yet) don't care about more granular events for MAU.
3. Adds new counter events to provide extra counters.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #293927 (closed)