Remove 'extended-redis-compatibility' config?

We originally decided to remove this config in Valkey 9.0. Valkey 9.0 is coming up, but we are still concerned of folks who might not yet have migrated yet and they may still benefit from having this compatibility.

Ref: https://github.com/valkey-io/valkey/commit/9e2b7838ea03c87a846bb3d47e60911f6eabba86