Improve sidekiq-catchall configuration

We have a general problem in that catchall is actually two shards: one on K8s and one on VMs. If we could at least help simplify the configs here, that would also help us roll this out.

These are the current configs: https://ops.gitlab.net/gitlab-cookbooks/chef-repo/-/blob/8f268c28d51f133baf32cef7c3ea6333d83fe88f/roles/gprd-base-be-sidekiq-catchall.json#L23 / https://gitlab.com/gitlab-com/gl-infra/k8s-workloads/gitlab-com/-/blob/207b7bd930cfb33cfabf6069a8b2444278a2af3f/releases/gitlab/values/values.yaml.gotmpl#L1003