[FIX] base: add a smart button on category related to partners

When we add a smart button on a contact tag related to contacts, the
button adds a default search filter that hides the related records

Steps to reproduce:
1. Install Contacts and Studio
2. Go to Contacts > Configuration > Contact Tags
3. Open tag "Vendor / Desk Manufacturers"
4. Toggle Studio
5. Add a button (at the top right of the form) related to field "Tags
   (Contact)"
6. Close Studio
7. Click on the button
8. A list view of the related contacts opens but there is a filter that
   hides the records

Solution:
Remove the `filter_domain` attribute on the field category_id and
replace it by the `operator` attribute in order to use the raw value in
the domain

Problem:
In `_getFieldDomain`, we replace the `self` in the domain by the
stringified id which essentially checks for a category that has a name
containing the id

opw-3471959

closes odoo/odoo#140564

X-original-commit: 18640a2ddddcf2ef90948295a41b0d7d30ec09e3
Signed-off-by: Rémy Voet (ryv) <ryv@odoo.com>
Signed-off-by: Guillaume Merlin (megu) <megu@odoo.com>

odoo/addons/base/views/res_partner_views.xml

@@ -431,7 +431,7 @@
                     <field name="parent_id" domain="[('is_company', '=', True)]" operator="child_of"/>
                     <field name="email" filter_domain="[('email', 'ilike', self)]"/>
                     <field name="phone" filter_domain="['|', ('phone', 'ilike', self), ('mobile', 'ilike', self)]"/>
-                    <field name="category_id" string="Tag" filter_domain="[('category_id', 'child_of', self)]"/>
+                    <field name="category_id" string="Tag" operator="child_of"/>
                     <field name="user_id"/>
                     <separator/>
                     <filter string="Individuals" name="type_person" domain="[('is_company', '=', False)]"/>