Remove isRecording from constructor (#6817)

It's an internal tracker that should not be modified while
instantiating.

Author: rlazo

firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/LiveGenerativeModel.kt

@@ -100,11 +100,7 @@ internal constructor(
     val receivedJson = webSession.incoming.receive().readBytes().toString(Charsets.UTF_8)
     // TODO: Try to decode the json instead of string matching.
     return if (receivedJson.contains("setupComplete")) {
-      LiveSession(
-        session = webSession,
-        backgroundDispatcher = backgroundDispatcher,
-        isRecording = false
-      )
+      LiveSession(session = webSession, backgroundDispatcher = backgroundDispatcher)
     } else {
       webSession.close()
       throw GeminiConnectionHandshakeFailed()

firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/type/LiveSession.kt

@@ -44,14 +44,14 @@ public class LiveSession
 internal constructor(
   private val session: ClientWebSocketSession?,
   @Background private val backgroundDispatcher: CoroutineContext,
-  private var isRecording: Boolean,
   private var audioHelper: AudioHelper? = null
 ) {
 
   private val audioQueue = ConcurrentLinkedQueue<ByteArray>()
   private val playBackQueue = ConcurrentLinkedQueue<ByteArray>()
   private var startedReceiving = false
   private var receiveChannel: Channel<Frame> = Channel()
+  private var isRecording: Boolean = false
 
   private companion object {
     val TAG = LiveSession::class.java.simpleName