[16.0][PERF] Improve journal ledger performance with lots of lines

[hugosantosred]

Improves the performance when obtaining the Journal Ledger with lots of account moves and lines.

For example in a demo database with 475K customer invoices before this changes the report in xlsx format is generated in 1900 seconds. With this changes is generated in 120 seconds

[aritzolea]

Code review. Thanks a lot for this huge performance improvement!

[liebana]

Functional review, LGTM.

[OCA-git-bot]

This PR has the approved label and has been created more than 5 days ago. It should therefore be ready to merge by a maintainer (or a PSC member if the concerned addon has no declared maintainer). 🤖

[pedrobaeza]

Better this way, thanks. The only missing thing is to comment in code before all the .id stuff that this technique is used for avoiding continuous recordset recreation, which affects dramatically the performance on systems with huge amount of journal items. This way, you avoid that in the future someone is tempted to restore the recordset thing.

[hugosantosred]

Better this way, thanks. The only missing thing is to comment in code before all the .id stuff that this technique is used for avoiding continuous recordset recreation, which affects dramatically the performance on systems with huge amount of journal items. This way, you avoid that in the future someone is tempted to restore the recordset thing.

Added the comment in the exigibility check