pantheon.switchboard-plug-pantheon-shell: 2.8.1 -> 2.8.2

Don't need pkgconfig override because of
* https://github.com/elementary/switchboard-plug-pantheon-shell/commit/d9971ebf1f0480a8501c547b7d2945f4ea93cef5

Patch to fix background permission issues is included in this release
so the downstream patch is dropped.

https://github.com/elementary/switchboard-plug-pantheon-shell/releases/tag/2.8.2