Improve compatibility with the Escalade plugin

[Lainow]

Checklist before requesting a review

Please delete options that are not relevant.

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• This change requires a documentation update.

Description

• Linked to : Fix _plugin_escalade_rules_only on group assignment escalade#489

Escalation treats each assigned group addition as an escalation: it retains only
the last assigned group, unassigns the technicians, and logs an escalation task.
This overrides the behavior of certain MoreOptions settings.

Here is the fix:

• “Use technician group” set to “All”: Groups are now added with the _plugin_escalation_rules_only flag, so that Escalation applies only business rules instead of triggering an escalation.
• The Escalation option “Use the technician group” takes precedence over the MoreOptions option “Take the technician group” when enabled and forces this option to be disabled on each entity.
• The ticket option is grayed out in the entity’s configuration form, accompanied by a warning, as long as the Escalation option is enabled.

Screenshots (if appropriate):