Reduce Docker Image Size

Installing packages on a Nuxeo Docker image keep the package content inside the folder NUXEO_HOME/packages/store/. To reduce the image size, it could be a good idea to cleanup this folder as its content should not be needed.

We want to study the impacts of removing the folder content after having installed the packages.

Moreover, we can also check if we can remove the content of the NUXEO_HOME/tmp folder at the end of the build.