Add script to automatically update containerd with newest cri plugin.

Signed-off-by: Lantao Liu <lantaol@google.com>

hack/test-integration.sh

@@ -29,7 +29,9 @@ mkdir -p ${REPORT_DIR}
 test_setup ${REPORT_DIR}
 
 # Run integration test.
-sudo ${ROOT}/_output/integration.test --test.run="${FOCUS}" --test.v
+# Set STANDALONE_CRI_CONTAINERD so that integration test can see it.
+# Some integration test needs the env to skip itself.
+sudo STANDALONE_CRI_CONTAINERD=${STANDALONE_CRI_CONTAINERD} ${ROOT}/_output/integration.test --test.run="${FOCUS}" --test.v
 test_exit_code=$?
 
 test_teardown