Keep retrying if pulling signaling messages fails

When the internal signaling server is used the observable to pull
signaling messages is subscribed again after each completion, but in
case of an error it was retried only 3 times. Those 3 times are not in a
row, though, but in total for the whole observable, no matter how many
times it was subscribed again.

Due to the limitation on retries in a long call with a flaky connection
pulling the signaling messages could fail more than 3 times, which
caused the observable to finish with an error and therefore stop further
pullings. In this situation the Android app would not notice if other
participants joined or left the call, and thus it would not establish a
connection with them or stop it. To prevent that now the number of
retries is unlimited (although the retry is still stopped if the local
participant is no longer in the call).

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

app/src/main/java/com/nextcloud/talk/activities/CallActivity.java

@@ -1480,7 +1480,7 @@ public class CallActivity extends CallBaseActivity {
                                 .observeOn(AndroidSchedulers.mainThread())
                                 .repeatWhen(observable -> observable)
                                 .takeWhile(observable -> isConnectionEstablished())
-                                .retry(3, observable -> isConnectionEstablished())
+                                .retry(observable -> isConnectionEstablished())
                                 .subscribe(new Observer<SignalingOverall>() {
                                     @Override
                                     public void onSubscribe(@io.reactivex.annotations.NonNull Disposable d) {