Ignore duplicate onEmergencyCallStarted case

In case there is another onEmergencyCallStarted invocation happens while onEmergencyCallStarted is in progress, let it ignored

Bug: 338469596
Test: atest SatelliteSOSMessageRecommenderTest
      manual test in live network to check whether overlapped event is ignored from the log
Change-Id: I64f25b0bddbb5121673056493461c81cc78a46f4