sysctl: enable coredump for suid binaries

sysctl: enable coredump for suid binaries

Right now the kernel will not dump anything that went through setuid or
setgid. But it is routine for daemons to do that, and it makes things hard to
debug.

systemd-coredump saves the coredump readable by the users the process was
running as. This should be enough to avoid information leakage. So let's also
tell the kernel to do the coredump.

For https://bugzilla.redhat.com/show_bug.cgi?id=1790972.

Both patterns are stored in the same file, so they are enabled or disabled
together. (Though suid_dumpable=2 is supposed to be safe even when writing to
plain files.)