This update introduces a simpler way to run Odoo tests by allowing users to use the '-t' alias for the --test-tags command. This change streamlines the testing process and makes it more convenient for developers. It's a minor improvement that enhances developer workflow.

Backport of https://github.com/odoo/odoo/pull/234287

<img width="408" height="151" alt="image" src="https://github.com/user-attachments/assets/7f22826f-6887-432b-8baf-8a6778b9cadf" />

Forward-Port-Of: odoo/odoo#250283
Forward-Port-Of: odoo/odoo#249123

This update enhances the testing process by clarifying documentation related to specific error codes (E8502 and E8505). The changes provide clearer explanations and examples, ensuring consistent and accurate testing of Odoo's translations.

- Update documentation link for E8502.
- Clarify why E8505 is in place and give an example.

Forward-Port-Of: odoo/odoo#251444