problem reporter: remove the update timer
This timer was introduced in 2007 and I'm not convinced it is needed. Back then, it was only for the problem reporter list view.
But these days, the inline note problem reporting is also dependent on this model, and there the 1 second delay is very annoying. When KDevelop is busy, it often goes up to the 5 seconds "long" variant, which feels like an eternity.