Various Plugins: Simplify return QList statements

Change-Id: I36633128e061d0544e4752a65804b460371283f7
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/todo/lineparser.cpp

@@ -79,7 +79,7 @@ QList<LineParser::KeywordEntry> LineParser::keywordEntriesFromCandidates(
 {
     // Ensure something is found
     if (candidates.isEmpty())
-        return QList<KeywordEntry>();
+        return {};
 
     // Convert candidates to entries
     std::vector<KeywordEntry> tmp;