MH-10485, Remove GStreamer Encoding Properties

The GStreamer Composer was removed but the encoding properties are still
in the configuration directory. Obviously, they can go away as well.

Signed-off-by: Lars Kiesow <lkiesow@uos.de>
Merged in lkiesow/matterhorn/t/MH-10485-remove-gsencoding-properties (pull request #305)

MH-10485, Remove GStreamer Encoding Properties