This change updates Field Service and Studio screens to reuse cached field information instead of repeatedly requesting it directly. It should make related pages more efficient without changing how users work.

The field service caches fields_get results. Here we replace some direct calls to fields_get via the orm by calls to the method loadFields of field service.

This internal change updates spreadsheet-related test utilities so they return the test environment needed by related checks. It helps keep spreadsheet sales and list testing aligned with the main platform changes, reducing maintenance risk without changing user-facing behavior.

This commit is the counterpart of https://github.com/odoo/odoo/pull/195552

Task: 4525938