Check dangerous use of scope via RuboCop rule
Problem
In https://docs.gitlab.com/ee/development/policies.html#scope we are warning the use of scope: :subject when more both user and subject are checked:
DANGER: If you use a :scope option when the condition actually uses data from both user and subject (including a simple anonymous check!) your result is cached at too global of a scope and results in cache bugs.
Proposed solution
Create a scope: :subject is used but user (or other receivers?) are used with a condition block.