Fix dropdown custom field search options

[cconard96]

Checklist before requesting a review

• I have read the CONTRIBUTING document.
• I have performed a self-review of my code.
• I have added tests that prove my fix is effective or that my feature works.

Description

Fixes #21162
Fix condition for dropdown custom field search option joins when multiple selection are allowed.
Fix usage of glpi_assets_assets table instead of REFTABLE in join conditions.
Add dropdown custom fields (single and multiple) to test dataset for automatic search tests to take them into account.

tests are failing

[trasher]

Tests are failing

[cconard96]

You cannot use CAST with JSON datatype. JSON is only a valid datatype in MySQL.

[cedric-anne]

You cannot use CAST with JSON datatype. JSON is only a valid datatype in MySQL.

Indeed, there is something missing to make this code compatible with both MySQL and MariaDB.

[cconard96]

You cannot use CAST with JSON datatype. JSON is only a valid datatype in MySQL.

Indeed, there is something missing to make this code compatible with both MySQL and MariaDB.

The point of the QueryFunction class refactoring was to allow better compatibility between DBMS. Maybe calls to cast with JSON type should be transformed to a JSON_EXTRACT function when MariaDB is detected, if there is a way currently to detect that.

I don't know how useful I am going to be today. I haven't had much sleep.