logrotate.conf: Simplify log files reopening after log rotation

logrotate.conf: Simplify log files reopening after log rotation

SIGHUP (1) signal makes ceph services reopen its log files so we do not
need to call any init scripts magic, here.

Additionally, the old approach caused problems with rhel-based systems
since it found the service command and tried to reload ceph.service
instead of ceph.target.

This also caused problems with SELinux as processes with context
logrotate_t are not allowed to issue systemctl reload on a process.

This patch is also in sync with other logrotate postrotate scripts which
do exactly the same thing (send SIGHUP to the daemon).

Signed-off-by: Boris Ranto <branto@redhat.com>