Remove TimelineTraceManager::State

This is redundant, now that we have registerFeatures().

Change-Id: Ia56c28b8892ab6da694570fe4b9ea5c96fe194f1
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qmlprofiler/tests/flamegraphmodel_test.cpp

@@ -98,7 +98,6 @@ void FlameGraphModelTest::initTestCase()
 {
     QCOMPARE(model.modelManager(), &manager);
     rangeModelId = generateData(&manager, &aggregator);
-    QCOMPARE(manager.state(), QmlProfilerModelManager::Done);
 }
 
 void FlameGraphModelTest::testIndex()