Follow-up on NETOBSERV-193 and on PoC NETOBSERV-219

As part of 4.12 goals, we want to have loki & strimzi installed as part of the operator installation.
This work is already done via NETOBSERV-219 (not merged, probably some rebase to do), however, at the moment we don't want to include prometheus and grafana (this is not in 4.12 target / downstream operator goals), so I would recommend to split in two different tasks / PRs, and start with only loki+strimzi.

We should make the subscriptions optional / configurable, for instance, by externalizing them via yaml files. We can possibly use go embed to integrate these files into the code, if necessary. The goal is to have different subscriptions depending on if it's an upstream or downstream build.