Use a path, which contains the namespace and the repo name instead of
the complete URL when triggering the Cerbero CI pipeline. Some of the
jobs in the Cerbero pipeline (specifically the examples build) need to
curl the API, and they need the path for that, not the website or git
URL.
The examples build doesn't use gst-plugins-rs, but we change this at
the same time as the monorepo for consistency.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1900>
