agent: Don't require stream names to parse remote SDP

The streams are matched by the order in which they appear in the SDP,
not by name, so insisting on local streams to have one makes no sense.

This likely should have been removed in 5972db04.
1 job for parse-remote-sdp in 52 seconds (queued for 3 minutes and 51 seconds)
Status Job ID Name Coverage
  Build
passed #63309
build-and-test

00:00:52