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. ^_^

Start in pkg/offering/base/ca/ca.go around line 496 and inspect how the {org}-ca and {org}-tls-ca secrets are created and whether anything consumes them. Determine with the maintainers whether they should be removed or contain the initial admin user, then verify the resulting secrets with kubectl.

Written by the indexing model from the issue text.