Minor refactor for configs (#172)

* Changes shard struct to use vector of ServerConfig

* Adds to query router

* Change client disconnect with error message to warn instead of debug

* Add warning logs for clean up actions

src/server.rs

@@ -591,6 +591,7 @@ impl Server {
         // server connection thrashing if clients repeatedly do this.
         // Instead, we ROLLBACK that transaction before putting the connection back in the pool
         if self.in_transaction() {
+            warn!("Server returned while still in transaction, rolling back transaction");
             self.query("ROLLBACK").await?;
         }
 
@@ -600,6 +601,7 @@ impl Server {
         // send `DISCARD ALL` if we think the session is altered instead of just sending
         // it before each checkin.
         if self.needs_cleanup {
+            warn!("Server returned with session state altered, discarding state");
             self.query("DISCARD ALL").await?;
             self.needs_cleanup = false;
         }