Reading ELEVATE_ONLINE and ELEVATE_RESUMABLE configuration while selecting maxdop

[tejaspan]

Fixes # .

Error when running cstore_doMaintenance on Azure database.

Changes proposed in this pull request:

• ELEVATE_ONLINE and ELEVATE_RESUMABLE configuration are in public preview which has 'OFF' value rather then zero, this will convert 'OFF' to zero.

How to test this code:

• Run it on latest azure database check for mentioned configuration which are on public preview and on OFF or ON state.

Has been tested on (remove any that don't apply):

• Azure SQL DB

[tejaspan]

select * from sys.database_scoped_configurations

[BrentOzar]

Tested on SQL Server 2019 (which has the same issue), and it worked there. I'll do a separate PR for the SQL Server 2019 version.