When heartbeat thread of ironic-conductor server is reporting heartbeat,
it will be interrupted by database exceptions except 'DBConnectionError'.
So add 'Exception' in _conductor_service_record_keepalive to catch all
possible exceptions raised from database to ensure the heartbeat thread
not to exit. And also log the exception information. When the database
recovers from an exception, heartbeat thread will continue to report
heartbeat.
Change-Id: I0dc3ada945275811ef7272d500823e0a57011e8f
Closes-Bug: #1696296
56b8eae918