[IMP] account: Exclude Off Balance Accounts from tax repartition lines

This commit excludes off-balance accounts from appearing in tax
repartition lines.
Previously, off-balance accounts were included in the selection, which
was causing confusion and unnecessary clutter in the interface.

The need for this change was raised due to the observation
that off-balance accounts are never actually used in tax repartition
scenarios.
Including them only complicates the account selection process without
adding any functional value

closes odoo/odoo#135763

Signed-off-by: Brice Bartoletti (bib) <bib@odoo.com>