Remove "name" field from Metric Definition

Problem

The name field in the metric definition currently serves no actual purpose, since it is not used in the code. It rather places a burden on the developer to come up with one more text value and its relationship with the keypath is unclear to anyone form just reading the documentation.

Proposed solution(s)

• Remove the name field from all metrics with one.
• Remove the name field from the metric definition and its usage, which should only be in generators.
• Remove the name suggestion generator, see https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/usage/metrics/name_suggestion.rb