Patch Rails 7 for CI partitioning

What does this MR do and why?

Related to #377521 (closed) and #377940 (closed)

It will allow us to cascade the partition_id filter through scoped associations and joins. This is the minimal and least invasive patch that I could think of and would not block us from switching to Rails native solution down the line.

Usage

class Job < ApplicationRecord
  belongs_to :pipeline,
    -> (build) { where(partition_id: build.partition_id) },
    partition_foreign_key: :partition_id # used for the join filter
  
  # To control the join filter
  def self.use_partition_id_filter?
    Feature.enabled?(...)
  end

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.