[16.0] mis_report: Added rows of accounts with no data in the comparison periods

[victoralmau]

It seems to be a side effect of the changes added in #584 (it was working correctly before).

Example use case:

• Create a mis report and use the template “Pérdidas y ganancias completo (PGCE 2008)” added by l10n_es_mis_report from OCA/l10n-spain.
• Define the comparison mode (2023 vs 2024).
• Click on preview/print/export
• Rows of all accounts will be displayed (even if there is no data in 2023 and 2024 for that account).

Before the change of the initially indicated PR (or in v15) the rows of the accounts without data in the periods were not added.

Ping @sbidoul

[victoralmau]

@sbidoul Sorry, have you had time to review this problem? I know it is related to the indicated PR but I am not very clear about the proper fix.

[sbidoul]

A fix for this is in #667