[FIX] web: Kanban: avoid ghost records when moving record

In an empty kanban view, when moving a freshly created record from
the second column to the first one, then moving it back again in to
the first one, the record was mysteriously duplicated.

When moving the record, it should be removed from the old column.
In this case, the second column was not found (and thus the record
not removed) because the iteration was on `parent.count` (which is
the count of records in this datapoint (1 in our case)) and not
parent.data.length (the number of columns).

0 files changed, 0 insertions, 0 deletions