COM_RESET_CONNECTION doesn't clear out session command history

Executing a COM_RESET_CONNECTION does not clear out the history that's stored. The COM_RESET_CONNECTION should clear out all stored session commands as well as all prepared statements which it doesn't currently do.

The error manifests as increased memory and CPU usage whenever the connector uses a COM_STMT_PREPARE, COM_STMT_EXECUTE, COM_RESET_CONNECTION style loop without explicitly closing the statements with COM_STMT_CLOSE.