Allow to change log verbosity without restarting the controller

[masayag]

The current implementation of flotta's logging is done by watching a configmap.
When the log_level element of that map is changed, the pod is being restarted.
While this allows to apply new log verbosity level in all operators, there are less desired side-effects, such as
initializing the entire-cache (depends on the scale, can take sometime + introduce unnecessary load on etcd/api-server).

Using https://pkg.go.dev/go.uber.org/zap#AtomicLevel, the log verbosity could be changed on the fly.
We'd like to explore that approach and to minimize the restarted when can be avoided.