screen-cast-stream: Don't broadcast PipeWireStreamAdded signal

The helper function from gdbus-codegen broadcasts the signal emission,
but we really only care about sending it to the specific peer that
created the session. Thus, only emit the signal to the particular peer
that owns the session.

https://bugzilla.gnome.org/show_bug.cgi?id=784199
2 jobs for wip/dont-broadcast-stream-added in 8 minutes and 44 seconds (queued for 3 seconds)
Status Job ID Name Coverage
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passed #200656
build-mutter

00:02:07

 
  Test
passed #200657
test-mutter

00:06:37