This commit cleans up the utm.campaign form view:
* Don't display mailing related things if no mailings on the campaign or
if the campaigns were not activated in mass_mailing settings;
* Stat button for the mass mailings was wrong, it was displaying the number
of mails instead of the number of mailings;
* Remove unused global click ratio field all other fields/methods related
to its computation;
* Remove ab testing cta on campaign form;
* Add groups on mailing related fields to avoid access errors;
LINKS
Task ID 2074813 (FP request UTM refactor)
PR: #37185
qmo-odoo
af601da9be