Enable ff validity_checks by default

What does this MR do and why?

Enable ff validity_checks by default

Set validity_checks to true Enable ff validity_checks by default

Changelog: added EE: true

Note: In order to release the feature [GA] Validity Checks (&16890) in version 18.7, we need to either remove or set this feature flag (FF) to true by default. My merge request to remove the FF is failing due to an unknown, unrelated reason. Given the feature release deadline, we are moving forward with enabling the FF by default for now, and we will remove the FF in a follow-up. This required changing the FF status from "WIP" to "OPS."

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.