Patch for primary keys retrieval optimization

What does this MR do and why?

We're backporting a fix to improve the primary key retrieval method in activerecord.

References

• Increase in Postgresql CPU usage from Sidekiq
• query plan for the current vs improved versions of the method

Screenshots or screen recordings

Before	After

How to set up and validate locally

Cloned Rails repo and confirmed the presence of the patch commit in the following version of rails:

git tag --contains c93d1b09fcc013033af506b10fd60829267be85c

v8.1.0
v8.1.0.rc1
v8.1.1

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.