RATIONALE
Currently when an ir.model.fields is removed all tracking linked to it is
lost. Indeed field is required and has an ondelete cascade attribute set
to it. However we should keep tracking values as those made sense when
used and one could want to have access to this information.
SPECIFICATIONS
When removing fields set the field to False instead. Add a new field to
store fields information allowing to keep name, type and groups information
to allow displaying removed tracking values. Use this field only when a
field is removed to avoid duplicating field information when not necessary
and polluting the table.
Task-3499067 (Mail: keep tracking when unlinking fields)
Part-of: odoo/odoo#124182
Thibault Delavallée
a88381cc12