Expected Behavior:
I am able to set an CPU limit of my choosing or none at all.

Actual behavior:
a CPU limit value of `'0'` is injected into the   `observability-thanos-receive-default` STS

Reproduction Steps:

• Modify the MCO spec with the following patch:

apiVersion: observability.open-cluster-management.io/v1beta2
kind: MultiClusterObservability
metadata:
  name: observability
spec:
  advanced:
    receive:
      resources:
        requests:
          cpu: 300m
          memory: 768Mi
        limits:
          memory: 768Mi

or 

apiVersion: observability.open-cluster-management.io/v1beta2
kind: MultiClusterObservability
metadata:
  name: observability
spec:
  advanced:
    receive:
      resources:
        requests:
          cpu: 300m
          memory: 768Mi
        limits:
          cpu: 300m
          memory: 768Mi

• wait for MCO to be reconciled
• Observe that on the observability-thanos-receive-default StatefulSet that `spec.template.containers[0].resources.limits.cpu` is set to the string '0' instead of null in the case of the first patch or '300m' in the second.

This seems to be a bug that was introduced in 2.11 as I can reproduce this in 2.11 but not 2.10.