In CI tests, avoid making multiple copies of the library

[mwetter]

Currently, for each processor, the Buildings library is copied. This is about 320 MB each. This issue is to copy it once and make symbolic links for all other processors.

This also requires changing the working directory of Dymola to be one level up from Buildings.

[mwetter]

Note that use of symbolic links does not work as they are not visible in the docker.