useless secrets created for `ca` should be removed or make it useful

Well... 
When I saw secrets `{org}-ca` and `{org}-tls-ca` by `kubectl  get ...` ,I just don't know  what these for....
 
https://github.com/hyperledger-labs/fabric-operator/blob/main/pkg/offering/base/ca/ca.go#L496

Maybe we remove these two secrets or just store the initial `admin` user? This only makes people confusing if it has no use.  ^_^ 