Wipe initial 4KiB for non-zeroed thin volumes

Wipe initial 4KiB for non-zeroed thin volumes

If the thin pool has disabled zeroing  (created with -Zn), we at least
clear initial 4KiB of such thin volume (provisions 1st block).

If lvcreate is executed with '-an' command will abort (same way like we for
normal LV - however for normal LV option -Zn may skip clearing completely,
for thin volumes this option is not supported (applies only for pools).