tests/webrtc: fix tests for no libnice

webrtcbin will fail the state change to READY when libnice elements are
not available.
3 jobs for webrtc-test-fixes in 4 minutes and 4 seconds
Status Job ID Name Coverage
  Preparation
passed #49585
manifest

00:00:21

 
  Build
passed #49586
build fedora x86_64

00:01:23

 
  Full Builds
passed #49587
build android arm64 api28

00:02:18