Upgrade to Heimdall 2.4.8, container cleanup

The latest upstream version of Heimdall removes all of the build dependencies from the production container. This should significantly reduce the findings on this container.

Additionally, this fixes an issue where the Ironbank version of the container would not start properly due to NPM creating a folder at /home/node/.config which was owned by root which was causing errors when running as the Heimdall user.

Instead of using the Heimdall user, this container is now using the node user that comes with it.