(#19365) qt6: remove multimedia plugins

they are legacy from qt5, but never existed in qt6:
qt/qtmultimedia@805b106
qt/qtmultimedia@9814896
qt/qtmultimedia@aa441d6
qt/qtmultimedia@f16dbe1
qt/qtmultimedia@58e7401

fixes #19146

recipes/qt/6.x.x/conanfile.py

@@ -1205,24 +1205,8 @@ def _create_plugin(pluginname, libname, plugintype, requires):
             _create_module("MultimediaWidgets", ["Multimedia", "Widgets", "Gui"])
             if self.options.qtdeclarative and qt_quick_enabled:
                 _create_module("MultimediaQuick", ["Multimedia", "Quick"])
-            _create_plugin("QM3uPlaylistPlugin", "qtmultimedia_m3u", "playlistformats", [])
             if self.options.with_gstreamer:
-                _create_module("MultimediaGstTools", ["Multimedia", "MultimediaWidgets", "Gui", "gst-plugins-base::gst-plugins-base"])
-                _create_plugin("QGstreamerAudioDecoderServicePlugin", "gstaudiodecoder", "mediaservice", [])
-                _create_plugin("QGstreamerCaptureServicePlugin", "gstmediacapture", "mediaservice", [])
-                _create_plugin("QGstreamerPlayerServicePlugin", "gstmediaplayer", "mediaservice", [])
-            if self.settings.os == "Linux":
-                _create_plugin("CameraBinServicePlugin", "gstcamerabin", "mediaservice", [])
-                _create_plugin("QAlsaPlugin", "qtaudio_alsa", "audio", [])
-            if self.settings.os == "Windows":
-                _create_plugin("AudioCaptureServicePlugin", "qtmedia_audioengine", "mediaservice", [])
-                _create_plugin("DSServicePlugin", "dsengine", "mediaservice", [])
-                _create_plugin("QWindowsAudioPlugin", "qtaudio_windows", "audio", [])
-            if self.settings.os == "Macos":
-                _create_plugin("AudioCaptureServicePlugin", "qtmedia_audioengine", "mediaservice", [])
-                _create_plugin("AVFMediaPlayerServicePlugin", "qavfmediaplayer", "mediaservice", [])
-                _create_plugin("AVFServicePlugin", "qavfcamera", "mediaservice", [])
-                _create_plugin("CoreAudioPlugin", "qtaudio_coreaudio", "audio", [])
+                _create_plugin("QGstreamerMediaPlugin", "gstreamermediaplugin", "multimedia", ["gst-plugins-base::gst-plugins-base"])
 
         if self.options.get_safe("qtpositioning"):
             _create_module("Positioning", [])