fix #28336: Sending 'program change' message to JACK MIDI Out

Then we will get *changed* midi port and channel from from midi mapping and send a message to a different port/channel we wanted. The same thing with initInstruments(): we call sendEvent() which emits signal to call putEvent() in the RT thread.  Midi mapping could be changed too while emitting.
So, initInstruments() and initInstrumentsRT() are both sensitive to changing a midi mapping.