Prevent SQL server isolation level from failing

Prevent SQL server isolation level from failing

Fixed bug where SQL Server transaction isolation must be fetched
from a different view when using Azure data warehouse, the query
is now attempted against both views and then a NotImplemented
is raised unconditionally if failure continues to provide the
best resiliency against future arbitrary API changes in new
SQL Server versions.

Change-Id: I621b5089febe8ace136428fa133fde1a7e21cda4
Fixes: #3994