Remove old groups from test inventory (#7656)

We have released v2.16 of Kubespray already, so we can remove those
old groups from the test inventory as the TODO says.

tests/cloud_playbooks/roles/packet-ci/templates/inventory.j2

@@ -7,14 +7,6 @@ instance-{{ loop.index }} ansible_ssh_host={{instance.stdout}}
 [kube_control_plane]
 instance-1
 
-# TODO(oomichi): Remove all kube-master groups from this file after releasing v2.16.
-[kube-master]
-instance-1
-
-# TODO(cristicalin): Remove kube-node,k8s-cluster groups from this file after releasing v2.16.
-[kube-node]
-instance-2
-
 [kube_node]
 instance-2
 
@@ -25,13 +17,6 @@ instance-3
 instance-1
 instance-2
 
-[kube-master]
-instance-1
-instance-2
-
-[kube-node]
-instance-3
-
 [kube_node]
 instance-3
 
@@ -43,12 +28,6 @@ instance-3
 [kube_control_plane]
 instance-1
 
-[kube-master]
-instance-1
-
-[kube-node]
-instance-2
-
 [kube_node]
 instance-2
 
@@ -58,12 +37,6 @@ instance-1
 [kube_control_plane]
 instance-1
 
-[kube-master]
-instance-1
-
-[kube-node]
-instance-1
-
 [kube_node]
 instance-1
 
@@ -74,13 +47,6 @@ instance-1
 instance-1
 instance-2
 
-[kube-master]
-instance-1
-instance-2
-
-[kube-node]
-instance-3
-
 [kube_node]
 instance-3
 
@@ -100,14 +66,6 @@ instance-3
 instance-1
 instance-2
 
-[kube-master]
-instance-3
-instance-1
-instance-2
-
-[kube-node]
-instance-3
-
 [kube_node]
 instance-3
 
@@ -125,14 +83,9 @@ instance-1 etcd_member_name=etcd2
 instance-2 etcd_member_name=etcd3
 {% endif %}
 
-[k8s-cluster:children]
-kube-node
-kube-master
-calico-rr
-
 [k8s_cluster:children]
 kube_node
-kube_master
+kube_control_plane
 calico_rr
 
 [calico_rr]