periodic.conf: remove long deprecated security_daily_compat_var()

[michaelo]

Summary

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

PR: 275296
Approved by: jrm (mentor), otis (mentor)
MFC after: 1 month

[otis]

Adding cy@ as he might also want have a look (as it's src component).

[jrm]

The message in periodic.conf is clear.

	# Compatibility with old daily variable names.
	# They can be removed in stable/11.
	security_daily_compat_var() {
		local var=$1 dailyvar value

		dailyvar=daily_status_security${var#security_status}
		periodvar=${var%enable}period
		eval value=\"\$$dailyvar\"
		[ -z "$value" ] && return
		echo "Warning: Variable \$$dailyvar is deprecated," \
		    "use \$$var instead." >&2
		case "$value" in
		[Yy][Ee][Ss])
			eval $var=YES
			eval $periodvar=daily
			;;
		*)
			eval $var=\"$value\"
			;;
		esac
	}