Update ClusterGroup singular name

This PR updates the singular name of the ClusterGroup
CRD from "group" to "clustergroup". After this update,
the "kubectl get group" command will not return any
ClusterGroups. However, the most common way and the
documented way to return ClusterGroups using kubectl
have been to use "kubectl get cg" or "kubectl get clustergroups".

Signed-off-by: abhiraut <rauta@vmware.com>

build/yamls/antrea-aks.yml

@@ -255,7 +255,7 @@ spec:
     plural: clustergroups
     shortNames:
     - cg
-    singular: group
+    singular: clustergroup
   scope: Cluster
   versions:
   - name: v1alpha2

build/yamls/antrea-eks.yml

@@ -255,7 +255,7 @@ spec:
     plural: clustergroups
     shortNames:
     - cg
-    singular: group
+    singular: clustergroup
   scope: Cluster
   versions:
   - name: v1alpha2

build/yamls/antrea-gke.yml

@@ -255,7 +255,7 @@ spec:
     plural: clustergroups
     shortNames:
     - cg
-    singular: group
+    singular: clustergroup
   scope: Cluster
   versions:
   - name: v1alpha2

build/yamls/antrea-ipsec.yml

@@ -255,7 +255,7 @@ spec:
     plural: clustergroups
     shortNames:
     - cg
-    singular: group
+    singular: clustergroup
   scope: Cluster
   versions:
   - name: v1alpha2

build/yamls/antrea.yml

@@ -255,7 +255,7 @@ spec:
     plural: clustergroups
     shortNames:
     - cg
-    singular: group
+    singular: clustergroup
   scope: Cluster
   versions:
   - name: v1alpha2

build/yamls/base/crds.yml

@@ -1610,7 +1610,7 @@ spec:
   scope: Cluster
   names:
     plural: clustergroups
-    singular: group
+    singular: clustergroup
     kind: ClusterGroup
     shortNames:
       - cg