meson: don't build icles when tests are disabled
meson: don't build icles when tests are disabled

They are manual tests, so let them be controlled
via the tests option.

GStreamer/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good