[FIX] prefetch issues on computed/related fields (#18644)

When deciding to prefetch records (getting records from the cache with
no value for the field being fetched), if the field was computed
`determine_value` would just get all records, not limited by the normal
prefetch limit; for large recordsets this would generate gigantic
prefetch lists for records we may not need at all.

Fix by applying the `PREFETCH_MAX` limit to records from the cache as is
done in `_prefetch_field`.

Complementarily, when traversing related fields the prefetch
environment would be lost and every record would get an empty prefetch
environment, so the values would ultimately be read one by one.

Example: select (search) 1000 product.product records, access a
related field (e.g. categ_id) in a loop, on the first iteration the
system would first read 1000 templates, then it would read each
categ_id individually, resulting in >1000 SQL queries rather than the
~2 we would expect.

Fixes #18511

0 files changed, 0 insertions, 0 deletions