Comment # 4 on bug 1129476 from Ed Vaessen

I had the same problem.
Among many lines, the shutdown log showed these:

[ 77.019608] systemd-journald[473]: systemd-journald stopped as pid 473
[ 167.020886] systemd-shutdown[1]: Sending SIGKILL to remaining processes...
[ 167.027376] systemd-shutdown[1]: Sending SIGKILL to PID 484 (lvmetad). 

As I do not need the LVM, I deleted the following packages:

liblvm2app2_2
liblvm2cmd2_02
lvm2

The service has vanished and shutdown is no longer delayed now.