Fix admin id used in the peer-to-local session in messaging context. (#…

…8049)

Without this, trying to use NewExchangeToLocal to simulate an
unsolicited incoming message fails to do the right thing because we
end up not matching up the MRP ack to the message's exchange
correctly, since the admin ids mismatch.

src/messaging/tests/MessagingContext.cpp

@@ -64,7 +64,7 @@ SecureSessionHandle MessagingContext::GetSessionLocalToPeer()
 SecureSessionHandle MessagingContext::GetSessionPeerToLocal()
 {
     // TODO: temporarily create a SecureSessionHandle from node id, will be fixed in PR 3602
-    return { GetSourceNodeId(), GetLocalKeyId(), GetAdminId() };
+    return { GetSourceNodeId(), GetLocalKeyId(), mDestAdminId };
 }
 
 Messaging::ExchangeContext * MessagingContext::NewExchangeToPeer(Messaging::ExchangeDelegate * delegate)