Currently, the lint_test_runner is built and installed into the lint CI
image. This is problematic, because it triggers a full image build on
every change to its source code. Doing a build of the lint test_runner
on every run is easier and faster.
(Similar to the doc comment in ci/lint_imagefile)
Also, rename docker-entrypoint.sh to container-entrypoint.sh
Also, add copyright header to touched files.
