[webrtc-pc] Too many test links in the spec, some redundant (#2161)

jan-ivar has just created a new issue for https://github.com/w3c/webrtc-pc:

== Too many test links in the spec, some redundant ==
After https://github.com/w3c/webrtc-pc/pull/2156 merged, I see lots of test links in the spec, which is great! I'm not sure if they are in their final visual form yet (could they be smaller perhaps?), but I think there are too many of them right now, making it a bit hard on the eyes.

Some of them seem redundant. For instance, I don't think steps that create internal slots, like in [create an RTCRtpTransceiver](https://w3c.github.io/webrtc-pc/#dfn-create-an-rtcrtptransceiver) are JS observable, so there cannot be a test for this step.

The getters for these, like e.g. [sender](http://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiver-sender) already have test links, which should suffice I think, so we shouldn't need them on both places. cc @dontcallmedom 

Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/2161 using your GitHub account