cubicweb #6304946 rename_relation_type doesn't work with computed relations [validation pending]

it attempts to backport values from the old relation to the new, while one shouldn't 'write' computed relation

prioritynormal
typebug
done in3.20.10
load0.100
load left0.000
closed by#d89e9176d263 [migration] don't attempt to carry over values when renaming a computed relation
patch[migration] don't attempt to backport values on renaming of a computed relation [applied]