Provide a path to downgrade etcd-druid from v0.23.x to v0.22.y

[unmarshall]

How to categorize this issue?

/area control-plane
/area open-source
/kind bug

What happened:
v0.23.x version introduced the following new CLI flags:
--workers is replaced by --etcd-workers
--custodian-workers has been removed
--enable-etcd-spec-auto-reconcile replaces --ignore-operation-annotation
--etcd-components-webhook-exempt-service-accounts has been newly added

PR #883 adds the capability in v0.23 to ignore unknown CLI flags (see here). We will have to add similar capability in v0.22 and then in g/g both new and old CLI args can be set.

What you expected to happen:
It should be possible to downgrade from v0.23 to v0.22 even when there are changes in CLI args to start up etcd-druid.