Need to support old behavior of MB-32244

When the fix was made for MB-32244, it was under the assumption that documentation and release note would be sufficient. The field team has expressed that that this is not reasonable, and we have to retain old behavior until user chooses to upgrade their handlers. The same should be implemented for 6.0.3 and carried forward in 6.5 with suitable warnings in UI that an upgrade to handler is necessary and link to description of behavior change.