Add missing ActiveRecord models for ApprovalRules
What does this MR do and why?
Contributes to #440139
Problem
Our test suite relies on Rails models to be correctly defined in yml files. Several ApprovalRules models are missing, because they represent join tables and don't contain an actual functionality.
More details: !144014 (comment 1762104294)
Solution
Define missing models to fix failing tests.
Edited by Vasilii Iakliushin