[usability] Code model warnings/errors should not be shown alongside real compiler warnings/errors

Since a few months ago, Qt Creator started showing the code model warnings/errors alongside the real compiler warnings and errors in the Issues pane. That's extremely annoying, as it makes difficult to find the actual errors. Most of the time, the Clang model warnings appear below the actual issues, but sometimes they appear on top.

The simplest case is when editing Qt code, the Clang code model complains about qdoc markups that it doesn't recognise (Clang expects Doxygen markup). So almost every .cpp file that you work on from Qt has warnings that are irrelevant.

But it gets really incredibly annoying when there are false positive errosr. In the attached screnshot, you can see it showing almost 13000 errors, NONE of which are valid. That has to be a problem in the model, but even if that gets fixed, there's still a usability bug that mixes real (compiler) issues with possible (model) issues. Don't mix them.