UnitTests: Fix names and disable slow tests by default

Slow and very slow tests have now their own test category. We add SlowTest
for tests which are slower than ~5ms and VerySlowTest if they are slower
than ~100ms. They are disabled them by "-*SlowTest.*". If you have a faster
machine than most developers simply try lower values. The aim is that most
developers can execute the tests in under ~2s.

In the long run we should use dependency breaking and data sharing to
reduce the count of the slow tests.

Change-Id: I8578071258d7f89b2052709f3dd526ced811483f
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

tests/unit/unittest/clangcreateinitialdocumentpreamblejob-test.cpp

@@ -40,6 +40,8 @@ protected:
     ClangBackEnd::CreateInitialDocumentPreambleJob job;
 };
 
+using CreateInitialDocumentPreambleJobSlowTest = CreateInitialDocumentPreambleJob;
+
 TEST_F(CreateInitialDocumentPreambleJob, PrepareAsyncRun)
 {
     job.setContext(jobContext);
@@ -47,7 +49,7 @@ TEST_F(CreateInitialDocumentPreambleJob, PrepareAsyncRun)
     ASSERT_TRUE(job.prepareAsyncRun());
 }
 
-TEST_F(CreateInitialDocumentPreambleJob, RunAsync)
+TEST_F(CreateInitialDocumentPreambleJobSlowTest, RunAsync)
 {
     document.parse();
     document.setDirtyIfDependencyIsMet(document.filePath());