Fix alarm-threshold-update --query option

Currently, alarm-threshold-update command can not update its query
field, because the dest value is removed accidently so the query is
not put under threshold_rule dict. This patch simply adds it back.

Change-Id: I2eeaf8cbb26f506e097dafdcb6d0eae4ad7fec3e
Closes-Bug: #1313676
Merge "Fix alarm-threshold-update --query option"