Eliminated explicit permission grant to hafah_user (be haf_applications_group role member) since it is ineffective and error prone - noone from applications group can change permissions to preserved hive scheme.

docker entrypoint cleanup actions should send SIGINT to the python process only when Python-Hafah is effectively used.

1) use python3.8-slim as a base image instead of alpine line due to 'wheel' package manager problems
2) fixed bug in docker_build.sh spanw, which silently ignored internally thrown build errors