Remove sql insights from workbook gallery

[masree]

Summary

SQL Insights officially got retired on 31 December 2024. Removing its reference from workbook insights gallery

Screenshots

• If you added a template to a gallery, show a screenshot of it in the gallery view (which verifies its shows up where you expected).
  

  It is also good to show a screenshot of template content, so people can see what you expect it to look like, compared to what they see when they might run it themselves.

Validation

• Validate your changes using one or more of the testing methods.
  Validated, no SQL Insights under "Insights" gallery

  Make sure you've tested your template content. Fixing things while in PR is trivial. Hotfixing it later is very expensive; at the current time at least 3 teams are involved in a hotfix!

Checklist

• If you are adding a new template, gallery, or folder, add your team and folder/file(s) to the CODEOWNERS file at the root of the repo. CODEOWNERS entries should be teams, not individuals.
  When done correctly, this means that from then on your team does reviews of your things, not the workbooks team.
• Ensure all steps in your template have meaningful names.
• Ensure all parameters and grid columns have display names set so they can be localized.