chan_pjsip: fix music on hold continues after INVITE with replaces

In a three party scenario with INVITE with replaces, we need to
unhold the call, otherwise one party continues to get music on
hold, and the call is not properly bridged between them.

ASTERISK-30428

Change-Id: I5675df11e739be5226b328f8828d4b8d81fbefb4
(cherry picked from commit 1c5720b80226336f62359962850ffd0e5afd2ab7)