Currently 'forums_count' field on website is not correctly updated. Test
introduced recently show that
* at website create, counter is not computed;
* at forum create, counter is not computed;
Only updating a forum active flag, website value, or unlinking it recomputes
the counters.
Note that manually updating counters is required as forum with False website
are global forum, valid for all websites.
Finally rename 'forums_count' into 'forum_count'. Fields in Odoo are rarely
plural (more like 'forum_ids' / 'forum_count' for example, even if in our
case the 2many does not exist due to shared behavior).
Task-3240082 (Forum: Reorganize and lint module)
Part-of: odoo/odoo#114841
Thibault Delavallée
e33f28de85