https://gitlab.com/gitlab-org/gitlab/-/merge_requests/55132 extended the
existing Graphql/Descriptions cop to cover enum values.

Existing offenses were added to `.rubocop_manual_todo.yml`.

This commit is the autocorrection-generated changes that add missing
periods to enum value descriptions.

It was generated using:

    bundle exec rubocop ee/app/graphql app/graphql \
      --auto-correct \
      --only Graphql/Descriptions

https://gitlab.com/gitlab-org/gitlab/-/issues/322903