Remove Gitlab::Llm::ChatStorage::Redis storage class

Proposal

This issue is to achieve the following tasks for Switch to PostgreSQL from Redis in ChatStorage (&15713 - closed).

  • Remove Gitlab::Llm::ChatStorage::Redis.
  • Remove duo_chat_storage_postgresql_write feature flag.
  • Remove duo_chat_storage_postgresql_read feature flag.

PoC

See PoC MR PoC: Duo Chat Storage with PostgreSQL (Not For ... (!170230 - closed).

Edited by Shinya Maeda