Change expath package installation routine

[duncdrum]

L218-267 introduces another system dependency (CURL) which we can't guaranty to be present on container executors.

Using COPY to move the xar into the autodeploy folder of the images before the containers are started would remove the dependency, be slightly faster, and allow us to use container executors on CI.

The speed increases just for the install might be to small to mke much of a difference, however the overall effect on CI would be significant.