[FIX] registry: transitive dependencies of custom fields may not exist

This is related to
826c86e9

The case is the same,
a custom field with an invalid depends,
except that this time its through a transitive dependency.
e.g.
custom_field_2 depends on custom_field_1
custom_field_1 depends on unexisting_field

The loading of the registry completely fails,
because the loading of the field `custom_field_2` raises a
`KeyError` exception in
`def transitive_dependencies` @ `dependencies[field]`
because the `custom_field_1` was skipped @ line
`dependencies[field] = set(field.resolve_depends(model))`

Landing in a state where the server can no longer start at all,
and the user can't therefore solve its custom field himself
to repair the situation.

closes odoo/odoo#51057

X-original-commit: 7b642884
Signed-off-by: Denis Ledoux (dle) <dle@odoo.com>