lint: Use $CI_RETRY_EXE when building ./ci/lint_imagefile

Previous code was confusing and brittle. For example, the full import
"source ./ci/test/00_setup_env.sh" and $PATH overwrite was not needed.

Fix it by simply copying the exe to /ci_retry and use that in
$CI_RETRY_EXE.

This is also a fix, because previously ci/lint_imagefile did use an
empty $CI_RETRY_EXE.

ci/lint_imagefile

@@ -9,6 +9,7 @@ FROM debian:bookworm
 ENV DEBIAN_FRONTEND=noninteractive
 ENV LC_ALL=C.UTF-8
 
+COPY ./ci/retry/retry /ci_retry
 COPY ./.python-version /.python-version
 COPY ./ci/lint/container-entrypoint.sh /entrypoint.sh
 COPY ./ci/lint/04_install.sh /install.sh