Rmove user id and user group id from docker files for runner and aggregator

Docker files for both the runner and aggregator contains the argument to setup the user and user group:

# Set defaults for build arguments
ARG USER_UID=2323
ARG USER_GID=2323

This breaks under some circumstances like the UB and CHAIMELEON node. It should be removed from the docker files and included in the command line from the launcher.json in FEM (external framework where this tool can be used) if required.