chutney: automate discovery and use of different tor versions
Building on #17015 (moved), we could:
- Preserve the old path before test-network.sh modifies it, and use the first tor in that path (#17015 (moved))
- Check for /usr/bin/tor and /usr/local/bin/tor (And maybe /opt ?) (#17015 (moved))
- Check the version of each tor binary, find a minimal set of different tor versions, then use each version in a round-robin fashion