[IMP][16.0] project_sequence: set analytic's code as per project's sequence_code

[arnaudlayec]

Before, the project's display_name was synched in the project's analytic account (aac) name. This way, the "code" field of aac was empty, and the name had both the project's code and the name in the default format "[code] - [name]" Proposal : synch the 2 fields ("sequence_code" and "name") of the project respectively in the 2 fields ("code" and "name") of the aac

This allow:

• standard display of aac (see aac's display_name method)
• ability to target aac with according project's code. Can be useful when importing account move and needing to set an analytic_distribution using the aac's code

This PR also update tests.
I needed to fix some:

• default_plan_id must be computed once to exist
• the 2 following tests cannot coexist. I aligned the code & tests like in v18.0 : test_project_without_sequence and test_project_with_empty_sequence. Doing that required to change project's create method

Note: if OK, I can port to upper version.

[OCA-git-bot]

Hi @anddago78, @yajo,
some modules you are maintaining are being modified, check this out!

[yajo]

Please could you share screenshots or screencast to see how it was before and how it is now? I think that will make it easier to review.

Code looks OK. Just one doubt.

[arnaudlayec]

Please could you share screenshots or screencast to see how it was before and how it is now? I think that will make it easier to review.

Code looks OK. Just one doubt.

Thank you for your review!
Yes indeed, a quick Screencast here (00:32), with hr_timesheet installed so project's analytic account is created right at project creation.

Screencast.from.2026-01-20.14-08-38.mp4

Se how Analytic Account's field "code" is filled in, as per project's sequence code: