Description of problem: When the MCE subscription is set with a config defined and the MCH controller tries to apply the MCE subscription without a config defined it will error.

Version-Release number of selected component (if applicable): 2.8.0

How reproducible: Always

Steps to Reproduce:

1. Set HTTP_PROXY in ACM subscription
2. Remove proxy from ACM
3.  

Actual results: MCE subscription can't be applied

Expected results: Apply is successful and MCE subscription matches ACM

Additional info:

Reconciler error {"controller": "multiclusterhub", "controllerGroup": "operator.open-cluster-management.io", "controllerKind": "MultiClusterHub", "multiClusterHub":

, "namespace": "open-cluster-management", "name": "multiclusterhub", "reconcileID": "08985ec6-3a2d-488f-bd0c-ac47f1fcf2cd", "error": "Subscription.operators.coreos.com \"multicluster-engine\" is invalid: spec.config: Invalid value: \"null\": spec.config in body must be of type object: \"null\""}