CI: simplify chutney installation
This is some cleanup in preparation for "cloning" the arti chutney-related CI into chutney's CI.
- Bump to a new version of chutney that supports referencing network configurations by name instead of by path.
- Replace usage of CHUTNEY_PATH with CHUTNEY_BIN. We no longer need the the chutney repository, just the actual chutney binary.
- Use pip to install directly from the chutney repository, without needing to clone it first.
And somewhat orthogonally to above, but related to cleaning up the chutney CI:
- Fix TODO of using virtualenv for pip package installation.
Edited by Jim Newsome