Move repo syncing code out of the Docker

[Kirill888]

There is currently a bash script baked into docker: sync_repo

https://github.com/GeoscienceAustralia/dea-sandbox/blob/develop/docker/assets/sync_repo

This should not be in the Docker, this a deployment concern and should be managed in the deployment repo(s). For example Africa and Australia deployments need different logic for installing dea-tools.

There is also question of changing current approach of dumping example directories directly into home folder, for more discussion see here #79.

CC: @NikitaGandhi