PURPOSE Simplify 'mail.tracking.value' model and code. Remove unnecessary fields and computation. Make code easier to handle and more batch-enabled. SPECIFICATIONS Remove 'field_desc' and 'field_type' from 'mail.tracking.value' model. Those can be retrieved when necessary, as it is mainly used for frontend display in Chatter. Task-3345979 (Mail: Simplify tracking model) Part-of: odoo/odoo#124182