Revert "proxy: update tokio-postgres to allow arbitrary config params (#8076)" (#8654)

This reverts #8076 - which was already reverted from the release branch
since forever (it would have been a breaking change to release for all
users who currently set TimeZone options). It's causing conflicts now so
we should revert it here as well.

proxy/src/serverless/backend.rs

@@ -236,10 +236,6 @@ impl ConnectMechanism for TokioMechanism {
             .dbname(&self.conn_info.dbname)
             .connect_timeout(timeout);
 
-        config
-            .param("client_encoding", "UTF8")
-            .expect("client encoding UTF8 is always valid");
-
         let pause = ctx.latency_timer_pause(crate::metrics::Waiting::Compute);
         let res = config.connect(tokio_postgres::NoTls).await;
         drop(pause);

proxy/src/serverless/sql_over_http.rs

@@ -203,7 +203,6 @@ fn get_conn_info(
             options = Some(NeonOptions::parse_options_raw(&value));
         }
     }
-    ctx.set_db_options(params.freeze());
 
     let user_info = ComputeUserInfo {
         endpoint,