When starting manually a CI pipeline with MESON_COMMIT variable defined,
install the specified version of Meson. This can be used to help the
Meson project smoke testing RC releases or investigate eventual
regressions.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3036>
Main differences with previous setup are:
- No manifest creation
- gst-indent is executed only when the bot is assigned (instead of the manifest task)
- Cerbero jobs are triggered in the cerbero repo
- Remove cerbero and android related files as they now are in cerbero
itself.
- Update `container.ps1` to the new file layout
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/891>