coredump: keep core files for two weeks

We have two mechanisms that remove old coredumps: systemd-coredump has
parameters based on disk use / remaining disk free, and systemd-tmpfiles does
cleanup based on time. The first mechanism should prevent us from using too much
disk space in case something is crashing continuously or there are very large
core files.

The limit of 3 days makes it likely that the core file will be gone by the time
the admin looks at the issue. E.g. if something crashes on Friday, the coredump
would likely be gone before people are back on Monday to look at it.

(cherry picked from commit f8d6713)

Related: RHEL-15501

tmpfiles.d/systemd.conf.in

@@ -59,7 +59,7 @@ a+ /var/log/journal/%m/system.journal - - - - group:wheel:r--
 {% endif %}
 
 d /var/lib/systemd 0755 root root -
-d /var/lib/systemd/coredump 0755 root root 3d
+d /var/lib/systemd/coredump 0755 root root 2w
 
 d /var/lib/private 0700 root root -
 d /var/log/private 0700 root root -