This adds `data_category: Optional` for all metric definitions except
the set of definitions that are meant to be part of the Standard
category: `uuid`, `hostname`, `license_subscription_id`, `license_md`.

  - Update tiers and distribution
  - Move the files under ee

  - Update data_source for Redis HLL metrics
  - Update tier free for metrics in core
  - Update distribution to ce for metrics in core

  - Import remaining metrics definitions
  - Generate metrics dictionary