Mark enrich.stats and indices.delete_data_lifecycle as private in Serverless (#3004)

* Mark enrich.stats and indices.delete_data_lifecycle as private in Serverless

These have INTERNAL scope now.

enrich.stats was updated here:
elastic/elasticsearch#107022

indices.delete_data_lifecycle was updated here:
elastic/elasticsearch#107607

* Update specification output

Author: picandocodigo