Dnn.platform: Make unique indexes unique

[sleupold]

Description of problem

Updated indexes in DNN 9.6.2 should be marked as "UNIQUE" to avoid SQL Server to add an unnecessary ID

Description of solution

CREATE UNIQUE NonClustered INDEX

Description of alternatives considered

none

Additional context

https://blog.sqlauthority.com/2019/07/24/sql-server-performance-impact-of-unique-index/

Affected browser

• [x] any

[sleupold]

I am going to submit a PR

[thabaum]

you simply ROCK man!

Thank you for sharing that article I hope it holds water :) very cool.

Also thank you for past contributions, I am definitely feeling some love in the performance area.

[stale[bot]]

We have detected this issue has not had any activity during the last 90 days. That could mean this issue is no longer relevant and/or nobody has found the necessary time to address the issue. We are trying to keep the list of open issues limited to those issues that are relevant to the majority and to close the ones that have become 'stale' (inactive). If no further activity is detected within the next 14 days, the issue will be closed automatically.
If new comments are are posted and/or a solution (pull request) is submitted for review that references this issue, the issue will not be closed. Closed issues can be reopened at any time in the future. Please remember those participating in this open source project are volunteers trying to help others and creating a better DNN Platform for all. Thank you for your continued involvement and contributions!

[sleupold]

still an issue, will submit a PR