`1.21` Attribute modifiers updates (#2637)
* Revert "patch for AttributeModifier UUID values"
This reverts commit 023bda77dae2a010e3fe023467c5a2da18091932.
* Initial attribute modifiers update
* Meta fixes
* Remove redundant variable
* `parseLegacyModifier`: `public` + `Deprecated`
* Fix deprecation warning format
* Fixes from review
(
commit: 95272dd)
