The Environment list is broken in Solution UI when there is a Namespace in Terminating Status

[ChengYanJin]

Component: ui, solution

What happened:
The Environment list does not display correctly when there is a namespace/environment on terminating status.

Got 404: https://10.200.4.124:8443/api/kubernetes/api/v1/namespaces/test/configmaps/metalk8s-environment

What was expected:
To be decided:
Do we consider to display the namespace on the list when it's in Terminating Status?

[root@metalk8sbootstrap centos]# kubectl get ns
NAME                  STATUS        AGE
default               Active        25h
kube-node-lease       Active        25h
kube-public           Active        25h
kube-system           Active        25h
metalk8s-auth         Active        25h
metalk8s-ingress      Active        25h
metalk8s-logging      Active        25h
metalk8s-monitoring   Active        25h
metalk8s-solutions    Active        25h
metalk8s-ui           Active        25h
test                  Terminating   19h
toto                  Active        19h
yanjin                Active        15h
yanjin-test           Terminating   20h

Why they are in terminating state?

apiVersion: v1
kind: Namespace
metadata:
  annotations:
    solutions.metalk8s.scality.com/environment-description: ""
  creationTimestamp: "2020-11-26T15:23:01Z"
  deletionTimestamp: "2020-11-26T15:27:14Z"
  labels:
    solutions.metalk8s.scality.com/environment: test
  name: test
  resourceVersion: "71785"
  selfLink: /api/v1/namespaces/test
  uid: 716f7b87-adf8-4d11-8b97-84c9ba862c53
spec:
  finalizers:
  - kubernetes
status:
  conditions:
  - lastTransitionTime: "2020-11-26T15:27:24Z"
    message: 'Discovery failed for some groups, 2 failing: unable to retrieve the
      complete list of server APIs: custom.metrics.k8s.io/v1beta1: the server is currently
      unable to handle the request, metrics.k8s.io/v1beta1: the server is currently
      unable to handle the request'
    reason: DiscoveryFailed
    status: "True"
    type: NamespaceDeletionDiscoveryFailure
  - lastTransitionTime: "2020-11-26T15:27:26Z"
    message: All legacy kube types successfully parsed
    reason: ParsedGroupVersions
    status: "False"
    type: NamespaceDeletionGroupVersionParsingFailure
  - lastTransitionTime: "2020-11-26T15:27:26Z"
    message: All content successfully deleted, may be waiting on finalization
    reason: ContentDeleted
    status: "False"
    type: NamespaceDeletionContentFailure
  - lastTransitionTime: "2020-11-26T15:27:32Z"
    message: All content successfully removed
    reason: ContentRemoved
    status: "False"
    type: NamespaceContentRemaining
  - lastTransitionTime: "2020-11-26T15:27:26Z"
    message: All content-preserving finalizers finished
    reason: ContentHasNoFinalizers
    status: "False"
    type: NamespaceFinalizersRemaining
  phase: Terminating

Steps to reproduce
Create a namespace and delete it from the UI.

Resolution proposal (optional):

[ChengYanJin]

Fixed in PR#2954