The `gstbuilddir` option has been removed by reverting the commit 879126a3. But the later commit 1babccfe503 uses the option within a test. Remove the mentioned option from the test. Fixes: 1babccfe503 Fix using overrides when not building PyGObject Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1743>