chore: mini refactorings and dead code removal (#5512)

src/util/Helpers.hpp

@@ -11,7 +11,7 @@
 namespace chatterino {
 
 // only qualified for tests
-namespace _helpers_internal {
+namespace helpers::detail {
 
     using SizeType = QStringView::size_type;
 
@@ -52,7 +52,7 @@ namespace _helpers_internal {
     std::pair<uint64_t, bool> findUnitMultiplierToSec(QStringView view,
                                                       SizeType &pos);
 
-}  // namespace _helpers_internal
+}  // namespace helpers::detail
 
 /**
  * @brief startsWithOrContains is a wrapper for checking