Improve timeout case

If session timeout is expired, server should send back to an error to the client.

Currently, server doesn't return any response to the client.

See also: https://github.com/apache/arrow-flight-sql-postgresql/issues/178#issuecomment-1847992730

Start by reproducing a request after the session timeout has expired and trace the server's handling of that case. Done means the server returns an error response to the client instead of returning no response; the linked discussion in issue 178 provides additional context.

Written by the indexing model from the issue text.