TT#61954 Set debhelper compat level in Build-Depends instead of debian/compat
- Stop copying debian/compat into the kernel source packages.
- Use dh_installsystemd instead of deprecated dh_systemd_*.
- Disable dwz as it cannot cope with some of the plugins generated.
Change-Id: Ibdc92e94955ef3c5d89b24fc341474236c49b986