Revert "Update containerd to 1.4.0-beta.0"

This reverts commit 7bcd610.

1.4.0-beta.0 fails with "containerd: symbol lookup error: containerd: undefined symbol: seccomp_api_set"

containerd/Dockerfile

@@ -19,7 +19,7 @@ RUN set -eux; \
 	runc --version
 
 # https://github.com/containerd/containerd/releases
-ENV CONTAINERD_VERSION 1.4.0-beta.0
+ENV CONTAINERD_VERSION 1.3.4
 
 RUN set -eux; \
 	wget -O containerd.tar.gz "https://github.com/containerd/containerd/releases/download/v${CONTAINERD_VERSION}/containerd-${CONTAINERD_VERSION}.linux-amd64.tar.gz" --progress=dot:giga; \