[10.x] Fix forced use of write DB connection

[oleksiikhr]

I am using Read & Write Connection (with a few tricks) and Laravel Octane.

My site is read-heavy, very few where I need to use write connection to work with DB. So most endpoints only require read DB connection.

Also, I started using a new feature from laravel 10.x, it's toRawSql, to simplify key creation for caching queries. As it turns out, queries that only require a read-only connection now also require a write connection to the database.

And at possible unavailability of write database, my site goes down, although it is quite enough only read-connection for processing current requests.

[taylorotwell]

I'm curious - could we just always use getReadPdo here? It will fallback to getPdo if it needs to based on my reading of the method. Am I wrong?