Fix qWarnings that come in expected situations

warnings are emitted during passing tests, for example:

[7229.542449951] [QTestLib] QWARN : tst_QFtp::get(WithSocks5ProxyAndSession:absPath02_1) QSymbianSocketEngine::setReadNotificationEnabled() was called on an uninitialized socket device

This particular warning is due to setReadNotificationEnabled(false) being called after the socket is closed.
A warning should be emitted only for setReadNotificationEnabled(true) on a closed socket, but we need to also take care not to recreate the socket notifier.

QWARN : tst_QNetworkReply::ioPostToHttpEmptyUploadProgress() QHttpNetworkConnectionChannel::_q_receiveReply() called without QHttpNetworkReply, 0 bytes on socket.

QWARN : tst_QNetworkReply::downloadProgress(empty) QNetworkAccessDebugPipeBackend::socketError() 1

QWARN : tst_QNetworkReply::ignoreSslErrorsList(SSL-failure-empty-list) could not set SSL_CTRL_SET_TLSEXT_HOSTNAME, Server Name Indication disabled

This seems to mean that symbian's open ssl library is too old?
In any case the warning comes for every https connection.

QWARN : tst_QTcpSocket::constructing(WithoutProxy SSL) CSymbianCertificateRetriever: failed to retrieve a certificate, error -46

Test needs ReadUserData capability

QWARN : tst_QTcpSocket::constructing(WithoutProxy SSL) QThread: Destroyed while thread is still running

?

QWARN : tst_QTcpSocket::setInvalidSocketDescriptor(WithoutProxy) QSymbianSocketEngine::initialize - socket descriptor not found
QWARN : tst_QTcpServer::setSocketDescriptor(WithoutProxy) QSymbianSocketEngine::initialize - socket descriptor not found

expected warning, need to ignore in test

QWARN : tst_QTcpSocket::delayedClose(WithSocks5Proxy) QAbstractSocket::waitForBytesWritten() is not allowed in UnconnectedState
This warning comes many times with SOCKS proxy but not for no proxy or HTTP proxy.
Suspect the socks socket engine is doing something strange here.

Checked qnetworkreply, qftp, qtcpsocket, qudpsocket, qtcpserver, qsslsocket and qsslsocket_onDemandCertificates_static autotests