Choppy persisted after every other dial-back. The only remaining new
Chrome-publisher params were the fullband pin and the 320k bump. Drop
both. Chrome publisher's SDP now back to the pre-feature shape
(stereo + FEC + 256k, no maxplaybackrate / sprop-maxcapturerate / cbr).
Kept: Firefox SDP regex fix, UA-gated NACK, speaker picker.