[16.0][FIX] partner_multi_relation: fix name search on relation

[NL66278]

Before this fix the following exception was logged (and the search not done):

2024-04-18 13:13:15,110 320 ERROR vwnvrs-testdatabase odoo.osv.expression: Non-stored field res.partner.relation.type.selection.display_name cannot be searched. 
NoneType: None

After fix no more errors in the log and the search works.

[SirAionTech]

Could you please explain how to obtain this error?
I tried to search for a relation in its Many2one field but the search is performed correctly and no ERROR is logged.

[NL66278]

@SirAionTech The error occurs if you have a model with a Many2one field to res.partner.relation.all, and then in the form you enter a name to search on.

[SirAionTech]

Thanks for the PR!
I had a look at the code and tested this change as you suggested in #1740 (comment):

The error occurs if you have a model with a Many2one field to res.partner.relation.all, and then in the form you enter a name to search on.

Everything looks fine.

Could you please add a test that fails without this fix? Searching for records is a feature I'd say is worth protecting from regression.

[github-actions]

There hasn't been any activity on this pull request in the past 4 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this PR to never become stale, please ask a PSC member to apply the "no stale" label.

[NL66278]

/ocabot merge minor

[OCA-git-bot]

Hey, thanks for contributing! Proceeding to merge this for you.
Prepared branch 16.0-ocabot-merge-pr-1740-by-NL66278-bump-minor, awaiting test results.

[OCA-git-bot]

Congratulations, your PR was merged at ab50512. Thanks a lot for contributing to OCA. ❤️