Purpose of this commit is to remove some complex check embedded in templates
and replace them by a computed unstored field. It eases definition and
understanding.
Its computation has been cleaned, so that sold out appears only when tickets
are really sold out, not if their end sales date is reached. Sold out label
is displayed in both event list and event specific page views in frontend.
Small spacing issues in frontend registration form are also fixed.
Task ID 2228189
Community PR odoo/odoo#48652
X-original-commit: c36cf90e7b83d2424b2f52ad8a2fec0bf367e8d8
Thibault Delavallée
bc1b5e134b