Reset Zotero prefs after each suite and when resetting DB

But keep prefs set in runtests.sh

test/content/support.js

@@ -511,7 +511,7 @@ var removeDir = Zotero.Promise.coroutine(function* (dir) {
  *                             any that were set at startup
  */
 function resetDB(options = {}) {
-	Zotero.Prefs.clear('lastViewedFolder')
+	resetPrefs();
 	
 	if (options.thisArg) {
 		options.thisArg.timeout(60000);