remove useless log in the PrepRequestProcessor#pRequest method

protected void pRequest(Request request) throws RequestProcessorException {
    // LOG.info("Prep>>> cxid = " + request.cxid + " type = " +
    // request.type + " id = 0x" + Long.toHexString(request.sessionId));
    request.setHdr(null);
    request.setTxn(null);