Ref: https://github.com/rails/rails/pull/50793

To make not caching connection checkout viable, we need to reduced
the amount of places where we need a connection.

Once big source of this is query/relation building, where in many
cases it eagerly quote and interpolation bound values in SQL fragments.

Doing this requires an active connection because both MySQL and Postgres
may quote values differently based on the connection settings.

Instead of eagerly doing all this, we can instead just insert these
as bound values in the Arel AST. For adapters with prepared statements
this is better anyway as it will avoid leaking statements, and for those
that don't support it, it will simply delay the quoting to just
before the query is executed.

However, the `%` API (`where("title = %s", something)`) can't realistically
be fixed this way, but I don't see much value in it and it probably should
be deprecated and removed.