systemd artful SRU

[Dimitri John Ledkov]

12.3 is currently phased at zero, due to increased crash rate which is
due to enablement of persistent journald.

Persistent journald causing watchdog timeout is an upstream
acknowledged issue, which I'm currently working on fixing/resolving.

12.4 reverts the enablement of the persistent journal, which should
reduce the rate of the crashes observed with 12.3.

Any other autopackage regressions observed with 12.4 were also
observed with 12.3 and retried into oblivion. The tiny clean revert
which is what 12.4 is has no direct effect on the observed autopkgtest
regressions. And thus 12.4 should be published and phasing restarted
to resolve the reasons why 12.3 phasing was stopped.

-- 
Regards,

Dimitri.