collab: Remove unused billing preferences queries (#34830)

This PR removes some billing preferences queries that are no longer in
use.

Release Notes:

- N/A

crates/collab/src/db.rs

@@ -42,9 +42,6 @@ pub use tests::TestDb;
 
 pub use ids::*;
 pub use queries::billing_customers::{CreateBillingCustomerParams, UpdateBillingCustomerParams};
-pub use queries::billing_preferences::{
-    CreateBillingPreferencesParams, UpdateBillingPreferencesParams,
-};
 pub use queries::billing_subscriptions::{
     CreateBillingSubscriptionParams, UpdateBillingSubscriptionParams,
 };