Disable JSON_PRETTIER validation in super-linter (#10186)

* Initial plan

* Disable JSON_PRETTIER validation in super-linter

Users experiencing JSON_PRETTIER errors during CI runs. Similar to how
VALIDATE_MARKDOWN_PRETTIER is already disabled, this disables JSON prettier
formatting checks while keeping JSON syntax validation active.

This allows contributors to focus on documentation content rather than
strict formatting requirements. JSON syntax validation remains active to
catch actual errors.

Fixes issues seen in:
- https://github.com/dotnet/core/actions/runs/20015768377
- https://github.com/dotnet/core/actions/runs/19512527950
- https://github.com/dotnet/core/actions/runs/19270296751

Co-authored-by: jongalloway <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: jongalloway <[email protected]>

Author: Copilot

.github/workflows/super-linter.yml

@@ -34,5 +34,6 @@ jobs:
           VALIDATE_JSCPD: false
           VALIDATE_NATURAL_LANGUAGE: false
           VALIDATE_MARKDOWN_PRETTIER: false
+          VALIDATE_JSON_PRETTIER: false
           DEFAULT_BRANCH: main
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}