[database][android] reset transaction signalled state on await()

android/src/main/java/io/invertase/firebase/database/RNFirebaseTransactionHandler.java

@@ -71,6 +71,7 @@ public class RNFirebaseTransactionHandler {
    */
   void await() throws InterruptedException {
     lock.lock();
+    signalled = false;
 
     long timeoutExpired = System.currentTimeMillis() + 5000;