ci: Add test cases for CoCo image pulling without forked containerd

Additional tests are necessary to verify new feature that pulling image without forked containerd in CoCo.
1)image sharing on the host with dm-verity.
2)image pulling in the guest with nydus-snapshotter.

Fixes kata-containers#5763

Depends-on:github.com/kata-containers/kata-containers/pull/7676
Depends-on:github.com/confidential-containers/operator#251

Signed-off-by: ChengyuZhu6 <chengyu.zhu@intel.com>

Makefile

@@ -104,7 +104,11 @@ cc-containerd:
 # Run the Confidential Containers tests for kubernetes.
 cc-kubernetes:
 	bash -f .ci/install_bats.sh
+<<<<<<< HEAD
 	K8S_TEST_UNION="confidential/agent_image.bats confidential/agent_image_encrypted.bats confidential/sealed_secret.bats confidential/image_pulling_with_snapshotter.bats" \
+=======
+	K8S_TEST_UNION="confidential/agent_image.bats confidential/agent_image_encrypted.bats confidential/sealed_secret.bats" confidential/image_pulling_with_snapshotter.bats" \
+>>>>>>> 92a99087 (ci: Add test cases for CoCo image pulling without forked containerd)
 	bash integration/kubernetes/run_kubernetes_tests.sh
 
 # Run the Confidential Containers AMD SEV specific tests.