Don't stop audio until after CallKit audio session is deactivated

// FREEBIE

Signal/src/call/Speakerbox/CallKitCallUIAdaptee.swift

@@ -25,6 +25,7 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
     internal let notificationsAdapter: CallNotificationsAdapter
     internal let contactsManager: OWSContactsManager
     private let provider: CXProvider
+    let audioActivity: AudioActivity
 
     // CallKit handles incoming ringer stop/start for us. Yay!
     let hasManualRinger = false
@@ -60,6 +61,7 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
         self.contactsManager = contactsManager
         self.notificationsAdapter = notificationsAdapter
         self.provider = CXProvider(configuration: type(of: self).providerConfiguration)
+        self.audioActivity = AudioActivity(audioDescription: "[CallKitCallUIAdaptee]")
 
         super.init()
 
@@ -348,6 +350,7 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
 
         Logger.debug("\(TAG) Received \(#function)")
 
+        OWSAudioSession.shared.startAudioActivity(self.audioActivity)
         OWSAudioSession.shared.isRTCAudioEnabled = true
     }
 
@@ -356,6 +359,7 @@ final class CallKitCallUIAdaptee: NSObject, CallUIAdaptee, CXProviderDelegate {
 
         Logger.debug("\(TAG) Received \(#function)")
         OWSAudioSession.shared.isRTCAudioEnabled = false
+        OWSAudioSession.shared.endAudioActivity(self.audioActivity)
     }
 
     // MARK: - Util