fix/restore form opening so cancel button works properly

[Herafia]

Checklist before requesting a review

• I have read the CONTRIBUTING document.
• I have performed a self-review of my code.

Description

• It fixes !39956
• A self-service user couldn’t cancel a ticket because the cancel button was visible but not functional — the form opening was missing.

Screenshots (if appropriate):

[stonebuzz]

Discussed with @Herafia and @Rom1-B

We identified an issue with missing <form> tags in simplified interfaces, specifically on the "Cancel Ticket" button.

During the investigation, we found that the file templates/components/itilobject/layout.html.twig lacked clarity regarding the conditions required to display the <form> tags.

This PR aims to simplify and clarify the logic by systematically opening and closing the <form> tag when we are not within a specific template context.

[AdrienClairembault]

I think it create conflicts with the new followup form.

You can't add followups anymore:

[stonebuzz]

The checkFormOutput unit test has been updated.
Going forward, the HTML page may contain either one itil_form element (when creating a new ticket) or two — one for the main form and another for objects (followup / solution / document) creation forms added by footer.

[stonebuzz]

The checkFormOutput unit test has been updated. Going forward, the HTML page may contain either one itil_form element (when creating a new ticket) or two — one for the main form and another for objects (followup / solution / document) creation forms added by footer.

Don’t worry about this — we’re refactoring the code to properly handle unique forms, regardless of whether it’s for updating a ticket, adding a follow-up, or cancelling one, since they all point to the same front end as previously implemented

[AdrienClairembault]

The cancel ticket button doesn't seems to work with the latest changes, nothing happen when I click on it.