When an export translator is selected for Quick Copy, Quick Copy
initialization triggers translator initialization a few seconds after
startup, because the translator code needs to be available synchronously
for drag/drop. A Quick Copy test was changing the setting to BibTeX,
which was resulting in random timeouts after subsequent resetDB() calls
due to slow translator loading. This change skips initialization in test
mode. This might actually fix a lot of timeouts on Travis in the second
half of the tests...
This also resets the Quick Copy pref in those tests so that it's left at
the default, though really we should automatically reset all prefs after
all test groups and in resetDB().
