According to MXS-1644 the refreshing of users may cause a crash.
In that particular case, the refreshing is triggered by the
authentication failing due to the user having hit the
'max_user_connection' limit of the server.
That is, refreshing the users in the situation is never going to
change the end-result. With this change, the users will not be
refreshed in that case and hopefully the crash will be avoided.
Note that this is something of a workaround as the crash could not
be repeated and the refreshing of the users should obviously not
ever cause MaxScale to crash.
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