Stylelint: Clean up obsolete vendor prefixes (#43219)

* Clean up old vendor prefixes in CSS

* Fix two duplicate properties

* Add changelogs

* Oops, missed one

* Oops; restored errant line removals

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/14644812842

Upstream-Ref: Automattic/jetpack@97c3235

Author: tbradsha

CHANGELOG.md

@@ -11,6 +11,7 @@ This is an alpha version! The changes listed here are not final.
 
 ### Fixed
 - Linting: Fix more Stylelint violations.
+- Linting: Remove outdated vendor prefixes in stylesheets.
 
 ## [0.47.22] - 2025-04-14
 ### Fixed