Use agnhost instead of busybox for network test (#9390)

busybox container requires a root permission for ping.
For testing hardening method at CI, we need to switch to another image
which doesn't require the root permission for network testing.
On kubernetes/kubernetes repo, we are using agnhost which doesn't
require it. So this makes the test use aghhost image.

In addition, this updates the test manifest to specify securityContext
without any privilege.

tests/testcases/030_check-network.yml

@@ -1,8 +1,8 @@
 ---
 - hosts: kube_control_plane[0]
   vars:
-    test_image_repo: registry.k8s.io/busybox
-    test_image_tag: latest
+    test_image_repo: registry.k8s.io/e2e-test-images/agnhost
+    test_image_tag: "2.40"
 
   tasks:
   - name: Force binaries directory for Flatcar Container Linux by Kinvolk
@@ -53,12 +53,33 @@
     retries: 5
     delay: 5
 
-  - name: Run 2 busybox pods in test ns
-    command: "{{ bin_dir }}/kubectl run {{ item }} --image={{ test_image_repo }}:{{ test_image_tag }} --namespace test --command -- tail -f /dev/null"
+  - name: Run 2 agnhost pods in test ns
+    shell:
+      cmd: |
+        cat <<EOF | {{ bin_dir }}/kubectl apply -f -
+        apiVersion: v1
+        kind: Pod
+        metadata:
+          name: {{ item }}
+          namespace: test
+        spec:
+          containers:
+          - name: agnhost
+            image: {{ test_image_repo }}:{{ test_image_tag }}
+            command: ['/agnhost', 'netexec', '--http-port=8080']
+            securityContext:
+              allowPrivilegeEscalation: false
+              capabilities:
+                drop: ['ALL']
+              runAsUser: 1000
+              runAsNonRoot: true
+              seccompProfile:
+                type: RuntimeDefault
+        EOF
     changed_when: false
     loop:
-    - busybox1
-    - busybox2
+    - agnhost1
+    - agnhost2
 
   - import_role:  # noqa unnamed-task
       name: cluster-dump
@@ -131,8 +152,8 @@
     - item in pods_running
     with_items: "{{ pod_ips }}"
 
-  - name: Ping between pods is working
-    command: "{{ bin_dir }}/kubectl -n test exec {{ item[0] }} -- ping -c 4 {{ item[1] }}"
+  - name: Curl between pods is working
+    command: "{{ bin_dir }}/kubectl -n test exec {{ item[0] }} -- curl {{ item[1] }}:8080"
     when:
     - not item[0] in pods_hostnet
     - not item[1] in pods_hostnet
@@ -140,8 +161,8 @@
     - "{{ pod_names }}"
     - "{{ pod_ips }}"
 
-  - name: Ping between hostnet pods is working
-    command: "{{ bin_dir }}/kubectl -n test exec {{ item[0] }} -- ping -c 4 {{ item[1] }}"
+  - name: Curl between hostnet pods is working
+    command: "{{ bin_dir }}/kubectl -n test exec {{ item[0] }} -- curl {{ item[1] }}:8080"
     when:
     - item[0] in pods_hostnet
     - item[1] in pods_hostnet