fix(kubernetes): always create scylla agent config
fix(kubernetes): always create scylla agent config

For the moment, we always specify scylla agent config in the
ScyllaCluster CRD. But appropriate 'secret' gets created only when
Scylla manager gets installed. If not, we get following errors in
Scylla operator logs:

    "Event occurred" object="scylla/sct-cluster" kind="ScyllaCluster"
    apiVersion="scylla.scylladb.com/v1" type="Warning"
    reason="InvalidManagerAgentConfig"
    message="Can't gent agent token: can't get agent token:
        can't get secret scylla/scylla-agent-config:
            secret \"scylla-agent-config\" not found"

So, create this secret always properly populating it based on the
Scylla manager presence.

scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests