Fix connectivity regressions (#2780)
Fix connectivity regressions (#2780)

* Fix connectivity regressions

Switches back to addTrack, digging the transceivers out manually
to re-use, because the only way to group tracks into streams re-using
trasceivers from the offer is to use setStreams which FF doesn't
implement.

* Remove comments
matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk