Fix DB load balancing for Rails 7.2

What does this MR do and why?

Rails 7.2 introduces additional entry points to fetch a connection from a model so we must also override these and return the connection proxy

References

&17620 (closed)

How to set up and validate locally

This one's hard to validate, but we can verify that the Rails 7.2 pipeline passes with these changes: !203184 (closed)

MR acceptance checklist

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