Introduce PredicateMemoization cop

What does this MR do?

• Introduce PredicateMemoization cop
• Fix offenses. Clearly some of the ||= is worthless before this patch

Why was this MR needed?

Apparently this is pretty easy to miss! @stanhu awesome suggestion!

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Review
  • Has been reviewed by Backend

What are the relevant issue numbers?

Closes #41731 (closed)