Adjust the recent patch for reporting of deadlocked queries so that we report

Adjust the recent patch for reporting of deadlocked queries so that we report
query texts only to the server log.  This eliminates the issue of possible
leaking of security-sensitive data in other sessions' queries.  Since the
log is presumed secure, we can now log the queries of all sessions involved
in the deadlock, whether or not they belong to the same user as the one
reporting the failure.