QmlProfiler: Clean up assignment of initial details to events

- Build the displayname from the location only once per event
- Make sure Qt4 paint events show the "GUI Thread" label
- Remove useless "Animations" displayName. It isn't shown anywhere.

Task-number: QTCREATORBUG-12496
Change-Id: I823676499670fc019b5dbf225668f833d17076b8
Reviewed-by: Kai Koehne <kai.koehne@digia.com>