periodic.conf: remove long deprecated security_daily_compat_var()

This function is documented to be gone in after 11. Time to remove this
compat shim.

PR: 275296
Reviewed by: jrm (mentor)
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D44796

periodic: Fix periodic reports when log files are not compressed.

The modern zcat(1) is capable of handling compressed and uncompressed
text files, so we can simply use zcat command.

PR: 253168
Reviewed by: delphij
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D43357

Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

periodic: add support for .xz and .zcat compressed logs

Also improve temporary file usage in 200.accounting, add an xref to
zstd(1) to newsyslog.conf.5, and clarify in periodic.conf that
"daily accounting" means process accounting and "monthly accounting"
is login accounting.

PR: 253868
Reviewed by: allanjude
Approved by: blackend (mentor)
Differential Revision: https://reviews.freebsd.org/D29267

Move all periodic related config and scripts to usr.sbin/periodic/

This makes pkgbase easier by tagging these as CONFS so they are properly
tagged as config files.

Approved by: will (mentor)
Sponsored by: Essen Hackathon
Differential Revision: https://reviews.freebsd.org/D16553