jenkins-common: use debian 13 by default
The testsuites were still using debian 12, switch to the current stable
version (13).
This also gives us a much newer bpftrace version:
* Debian 12: 0.17.0-1
* Debian 13: 0.23.2-1
Change-Id: I231e1e93724faf6d659132be9b9d0e164502bf95
