When computing the todo fields of maintenance requests, we could get a `MemoryError` since we are fetching more fields that we actually need. Here we rework the way the compute is done in order to avoid too much prefetch. closes odoo/odoo#82662 X-original-commit: 510831013ba081edd83191a01d562485b6ceca38 Signed-off-by: Christophe Simonis <chs@odoo.com>