Remove `processGroupsToRemove` and `processGroupsToRemoveWithoutExclusion` for FoundationDBProcessGroup

[johscheuer]

Instead of using the processGroupsToRemove and processGroupsToRemoveWithoutExclusion a user should directly target the desired FoundationDBProcessGroup and set the remove flag there. This should trigger an exclusion and once the Pod is excluded the FoundationDBProcessGroup controller can remove all resources. This has the benefit that we don't have to maintain additional information in the cluster CRD. Also this allows us to stop the deletion of a FoundationDBProcessGroup by just setting remove back to false.

Design: https://github.com/FoundationDB/fdb-kubernetes-operator/blob/master/docs/design/process_group_crd.md