Docker v29 breaks dmake_wait_for_it

[vdel]

Docker v29 stop creating environment variables for links by default, which break dmake_wait_for_it.

To fix it, we need to set DOCKER_KEEP_DEPRECATED_LEGACY_LINKS_ENV_VARS=1.

See https://docs.docker.com/engine/release-notes/29/

Support for this will be dropped in v30.