gstreamer-tests: update pipelines for R32.5.0 plugins

The NV plugins in R32.5.0 handle caps negotiation differently,
so adjust the test pipelines to accommodate. For sinteltest,
replace gst-play-1.0 with a pipeline, since the auto-negotiated
caps don't work in all cases.

Signed-off-by: Matt Madison <matt@madison.systems>