Build documentation for rust plugins

Build documentation for rust plugins

- Update the docker image we use, starting using the standard one adding
  `gtk4-doc` as required by rust plugins
- Update the plugins_doc_caches as required, some more plugins are built
  with the new image
- Install ninja from pip as the version from F31 is too old
- Avoid buildings all GSreamer plugins when building the doc as it takes
  time and resources for no good reason
- Stop linking to `GInstanceInitFunc` as it is not present in latest GLib
  documentation, leading to warnings in hotdoc.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2954>