QNetworkReplyHttpImpl::_q_startOperation - remove a useless warning

Since it explains nothing and now, after some other bug was fixed
(see, for example, c89d0f9d532), we trigger this message on the
first request, which happens because:
- 'createSession()' indeed, creates a session, compares a previous
  kwnon state (which happens to be 'Invalid') with a current state,
  which is 'Connected' and then invokes '_q_networkSessionStateChanged'.
- '_q_networkSessionStateChanged()' on 'Connected' emits
  'networkSessionConnected()' to which a newly-created QNetworkReplyHttpImpl
  will respond with it's _q_startOperation().
- QHttpNetworkReplyImpl will also try to 'open' a session, its 'opened()'
  signal will trigger, again, 'networkSessionConnected()' and ... the
  next _q_startOperation().
Now, not to add even more twisted spaghetti if/conditions with some
unpredictable regressions, let's suppress a useless warning and
silently return. We, indeed, in 'Working' state, let's keep working.

Task-number: QTBUG-72463
Change-Id: I5282979920915ffded889c20b8ae740a46efef04
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/access/qnetworkreplyhttpimpl.cpp

@@ -1879,11 +1879,9 @@ void QNetworkReplyHttpImplPrivate::_q_startOperation()
 {
     Q_Q(QNetworkReplyHttpImpl);
 
-    // ensure this function is only being called once
-    if (state == Working) {
-        qDebug() << "QNetworkReplyHttpImplPrivate::_q_startOperation was called more than once" << url;
+    if (state == Working) // ensure this function is only being called once
         return;
-    }
+
     state = Working;
 
 #ifndef QT_NO_BEARERMANAGEMENT