tests(helpers) use `Entity.new` for plugins schema
tests(helpers) use `Entity.new` for plugins schema

Use `Entity.new` to instantiate `plugins_schema`; doing so keeps this
helper's implementation consistent with how plugins are loaded in the
plugins DAO, avoiding surprises - e.g., this makes sure nested record
fields have their default values populated.

Kong/kong,Kong/kong,Mashape/kong,Kong/kong