redis: introduce options for lazy freeing

This is part of backporting this production change into the config: gitlab-com/gl-infra/production#1766 (closed).

Lazy freeing is a new option that was introduced in redis 4. It allows performing frees of large objects (e.g. large lists or sets) into smaller frees, improving latency by not blocking the whole process.

refs https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/9420.