Fix container build after Ubuntu 21.10 reached EoL

Ubuntu archived short-term release 21.10 and moved it to the
old-releases.ubuntu.com site. We still have to use it because
older Docker versions are affected by moby/moby#42681

To fix the build switch apt sources to old-releases before installing
packages.

Change-Id: I0432cd0002b4e955399539a5b0ddaba21b4535cc
Reviewed-on: https://cos-review.googlesource.com/c/cos/tools/+/36309
Reviewed-by: Arnav Kansal <rnv@google.com>
Tested-by: Oleksandr Tymoshenko <ovt@google.com>
Cloud-Build: GCB Service account <228075978874@cloudbuild.gserviceaccount.com>

src/cmd/cos_kernel_devenv/Dockerfile

@@ -1,6 +1,8 @@
 FROM ubuntu:21.10
 
-RUN apt-get -y update && \
+RUN sed -i 's/archive.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list && \
+	sed -i 's/security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list && \
+	apt-get -y update && \
 	apt-get -y install apt-transport-https ca-certificates gnupg curl && \
 	echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] https://packages.cloud.google.com/apt cloud-sdk main" \
 	    > /etc/apt/sources.list.d/google-cloud-sdk.list && \