Revert "storcon: switch to diesel-async and tokio-postgres (#10280)" (#10592)

There was a regression of #10280, tracked in
[#23583](https://github.com/neondatabase/cloud/issues/23583).

I have ideas how to fix the issue, but we are too close to the release
cutoff, so revert #10280 for now. We can revert the revert later :).

storage_controller/src/main.rs

@@ -308,7 +308,7 @@ async fn async_main() -> anyhow::Result<()> {
     // Validate that we can connect to the database
     Persistence::await_connection(&secrets.database_url, args.db_connect_timeout.into()).await?;
 
-    let persistence = Arc::new(Persistence::new(secrets.database_url).await);
+    let persistence = Arc::new(Persistence::new(secrets.database_url));
 
     let service = Service::spawn(config, persistence.clone()).await?;