Clean up code

* Use compiler generated comparison function
* Use designated initializers
* Convert to proper type
* Use reference
* Remove redundant text
  The `msg` already contain the text `Reason:` so it isn't needed.

PR #20312.

src/base/bittorrent/dbresumedatastorage.cpp

@@ -148,7 +148,7 @@ namespace
     template <typename LTStr>
     QString fromLTString(const LTStr &str)
     {
-        return QString::fromUtf8(str.data(), static_cast<int>(str.size()));
+        return QString::fromUtf8(str.data(), static_cast<qsizetype>(str.size()));
     }
 
     QString quoted(const QString &name)