systemd-coredump in systemd versions >=246 uses zstd as the default.
Now having 247.1-3 in current Debian/bullseye, we should have zstd
available out-of-the-box for dealing with compressed coredump files
(which are zstd by default). Given that zstd is available also in
Debian/buster, let's add it to ngcp-services-{ce,pro}.
Change-Id: I7fddd253c93f32ec7cb8f38900feab73218b2cf9
Michael Prokop