migrate Nighthawk Docker image from Alpine to Ubuntu

[eric846]

Problem

We had to add -lrt -latomic when #1309 updated to the latest Envoy.

#1312 found that the Docker image no longer works because libatomic.so.1 is not found.

Solution

The minimal solution to add apk install libatomic was not sufficient to fix the issue because of unknown Alpine issues.

Migrating from Alpine to Ubuntu 22.04 and including RUN apt-get update && apt-get install libatomic1 appears to work. (Ubuntu SHA is copied from Envoy: https://github.com/envoyproxy/envoy/blob/f2023ef77bdb4abaf9feef963c9a0c291f55568f/ci/Dockerfile-envoy)

Just changing the FROM to Ubuntu 22.04, before adding apt-get install libatomic1, we start off with a similar error:

ci/do_ci.sh docker
docker run envoyproxy/nighthawk-dev:latest nighthawk_client
nighthawk_client: error while loading shared libraries: libatomic.so.1: cannot open shared object file: No such file or directory

After adding apt-get install libatomic1, the nighthawk_client executable can start:

ci/do_ci.sh docker
docker run envoyproxy/nighthawk-dev:latest nighthawk_client
Bad argument: A URI or --multi-target-* options must be specified.

It is a low risk to publish a new Docker image based on the minimal confirmation above. The image can't be worse than the current image on Docker Hub that doesn't work.