Remove PipeWire module and metainfo mention

-Don't need module since Element builds against Electron 13, which supports PipeWire 0.3
-PipeWire 0.3 is included in the runtime.
-Mentioning the flag in the metainfo descrption will be redundant as of the next Element release, see element-hq/element-web#18607

chat.schildi.desktop.metainfo.xml

@@ -18,7 +18,7 @@
     </ul>
     <p>Preliminary Wayland support now available.</p>
     <p>To try running SchildiChat natively under Wayland, run:</p>
-    <p>flatpak run chat.schildi.desktop --enable-features=UseOzonePlatform,WebRTCPipeWireCapturer --ozone-platform=wayland</p>
+    <p>flatpak run chat.schildi.desktop --enable-features=UseOzonePlatform --ozone-platform=wayland</p>
     <p>For GNOME, window decorations are currently missing and you'll have to use keyboard shortcuts instead to resize the window.</p>
   </description>
   <screenshots>

chat.schildi.desktop.yaml

@@ -81,21 +81,6 @@ modules:
         dest-filename: autogen.sh
         commands:
           - AUTOMAKE="automake --foreign" autoreconf -vfi
-  - name: pipewire
-    buildsystem: meson
-    config-opts:
-      - "-Dgstreamer=disabled"
-      - "-Dman=false"
-      - "-Dsystemd=false"
-    cleanup:
-      - "/include"
-      - "/bin"
-      - "/etc"
-      - "/lib/pkgconfig"
-    sources:
-      - type: git
-        url: https://github.com/PipeWire/pipewire.git
-        tag: 0.2.7
   - name: schildichat
     buildsystem: simple
     build-commands: