When a PJSIP channel is set on hold or off hold, all streams were set
on/off hold. This is not the desired behaviour and caused issues
when there were multiple streams in the topology.
Now, only the default audio stream is set on/off hold when a hold is
indicated.
ASTERISK-30051
Change-Id: I04f1110565fd05fea565f5539b534b54549d4f71