JSON: Fix validation being disabled following #13459 (#13770)

The problem with #13459 was the bump to a newer JSON LS version, which
requires explicitly opting into validation.

Release Notes:

- Fixed JSON validation being disabled by default (Preview only)
28c5e33e0cPiotr Osiewicz committed on 7/3/2024, 9:17:20 AM· committed by GitHubparent5c7a8f7
1 file changedLine totals unavailable