flatpak: Remove jack2 module

jack2 is already part of the runtime that we rely on and we use only its
headers.

CI/flatpak/com.obsproject.Studio.json

@@ -313,25 +313,6 @@
         }
       ]
     },
-    {
-      "name": "jack2",
-      "buildsystem": "simple",
-      "build-commands": [
-        "./waf configure --prefix=$FLATPAK_DEST",
-        "./waf build -j $FLATPAK_BUILDER_N_JOBS",
-        "./waf install"
-      ],
-      "cleanup": [
-        "*"
-      ],
-      "sources": [
-        {
-          "type": "archive",
-          "url": "https://github.com/jackaudio/jack2/releases/download/v1.9.14/v1.9.14.tar.gz",
-          "sha256": "a20a32366780c0061fd58fbb5f09e514ea9b7ce6e53b080a44b11a558a83217c"
-        }
-      ]
-    },
     {
       "name": "pipewire",
       "buildsystem": "meson",