Configure keep alive duration for okhttp connection pool to 1 minute.

The signal http server supports http keep alive, but closes idle
connections after 1 minute.
The default OkHttp connection pool will keep idle connections in the pool
for 5 minutes and doesn't notice it when the server closes connections.
As currently the automatic okhttp retries are disabled, reusing such a
stale connection will be fatal.

Issue is especially severe for incoming calls, which fail because the request
to retrieve the turn servers fails and isn't retried: #10787

libsignal/service/src/main/java/org/whispersystems/signalservice/internal/push/PushServiceSocket.java

@@ -138,6 +138,7 @@
 
 import okhttp3.Call;
 import okhttp3.Callback;
+import okhttp3.ConnectionPool;
 import okhttp3.ConnectionSpec;
 import okhttp3.Credentials;
 import okhttp3.Dns;
@@ -1807,6 +1808,8 @@ private static OkHttpClient createConnectionClient(SignalUrl url, List<Intercept
              .connectionSpecs(url.getConnectionSpecs().or(Util.immutableList(ConnectionSpec.RESTRICTED_TLS)))
              .build();
 
+      builder.connectionPool(new ConnectionPool(5, 45, TimeUnit.SECONDS));
+
       for (Interceptor interceptor : interceptors) {
         builder.addInterceptor(interceptor);
       }