build: copy python packages into /usr instead of ~ros2 to avoid permission issues

[LouisBrunner]

Description

Part of aica-technology/docker-images#78

Review guidelines

Estimated Time of Review: 5 minutes

Checklist before merging:

• Confirm that the relevant changelog(s) are up-to-date in case of any user-facing changes

[domire8]

Should we use that to test if it works as expected once control libraries is merged or did you already do that locally?

[LouisBrunner]

Should we use that to test if it works as expected once control libraries is merged or did you already do that locally?

I used a packaged backend, moved all of the ~ros2/.local/lib/python3.10/site-packages to /usr/lib/python3.10/dist-packages and ran python -c 'import clproto' and it found the library.
On the other hand, I built this image and checked that the packages were correctly copied to /usr/lib/python3.10/dist-packages.

[domire8]

Thanks!