Filed on behalf of Maor Friedman

----

Hello,

When setting up a new cluster in OCM, I have added users to the dedicated-admins group via OCM.
This group and the users are reflected in: `oc get group dedicated-admins`.

When removing a user from the group using `oc adm groups remove-user dedicated-admins <user>`, the change was not reflected in OCM.

I'm not sure what is the expected behavior though.
This PR is related as it enabled dedicated-admin to get/list groups: https://github.com/openshift/managed-cluster-config/pull/235

In addition, this is what happens when trying to delete a group:
```
$ oc delete group test-group
Error from server: admission webhook "group-validation.managed.openshift.io" denied the request: Invalid request
```
Not sure if this is expected as well.

Thank you!
Maor Friedman