There are several configure settings that should have different default values depending on if configure is run as part of a CI build, or a local developer.

We should have a `--with-build-env=ci/dev` argument that lets you chose such build environment. Furthermore, configure should look for the industry standard "CI" environment variable to determine if it is running in a CI environment, and if so, select the ci build env as default. (This is supported e.g. by GHA).