[FIX] account: fix complex tax computations (multiple price included taxes, etc.)

Suppose the correct computation:

        seq | amount | incl | incl_base |  base  |  amount
        ----------------------------------------------------
          1 |    10% |    t |         t |  100.0 |     10.0
          2 |    10% |      |           |  110.0 |     11.0
          3 |    10% |    t |           |  110.0 |     11.0
          4 |    10% |      |           |  110.0 |     11.0
          5 |    10% |    t |           |  110.0 |     11.0
        ----------------------------------------------------

with an initial amount of 132. Without this commit, the base amount was computed by:

132 / 1.1 / 1.1 = 109.09

instead of:

132 / 1.2 = 110.0

see task: https://www.odoo.com/web#id=34471&view_type=form&model=project.task&action=333&active_id=967&menu_id=4720

Was PR #18275