[FIX] account: recompute draft move name on journal change

With the name calculation change in
9bf54f09, we missed the case to
recompute the name of a move on a journal change. It seems a test case
for this was missing an assert.

This commit fixes the behavior, so the move name is now correctly
recomputed again when changing the journal. The test has also been
amended.

task-3326834

closes odoo/odoo#121920

Signed-off-by: William André (wan) <wan@odoo.com>