polldaemon: fix missing mirror in-sync info with lvmpolld

polldaemon: fix missing mirror in-sync info with lvmpolld

CONVERTING status flag is a tricky one. It's not set when converting
a non-mirror LV type to the mirror type, i.e.: linear -> two leg mirror.
Also the conversion itself is instant and doesn't require to be polled.
When mirror reaches sync state there's no final update on VG metadata
for lvmpolld to be made thereby report_progress in fact doesn't report
percentage of mirror being converted but percentage of mirror
being in sync. Perhaps we should reword the lvconvert output here.

On the other hand CONVERTING is set while we upconvert the mirror
from i.e. two leg mirror to four leg mirror. In such case the operation
is required to be polled so that lvmpolld can cleanup temporary
conversion log when the conversion is over.

Ignore CONVERTING lv_type for the moment and match LVs only by uuids
during 'mirror conversion'/'waiting for a sync to finish'.