CppTools: Qt6: Drop use of QTextStream::setEncoding from CppFileSettings

This now requires license templates file to be Unicode compatible,
effectively restricting it to plain ASCII in non-Unicode codebases.

Task-number: QTCREATORBUG-24098
Change-Id: I713fed1ddb288360abbdbb40c6ca67444eb62ef3
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/cpptools/cppfilesettingspage.cpp

@@ -237,7 +237,6 @@ QString CppFileSettings::licenseTemplate()
     }
 
     QTextStream licenseStream(&file);
-    licenseStream.setCodec(Core::EditorManager::defaultTextCodec());
     licenseStream.setAutoDetectUnicode(true);
     QString license = licenseStream.readAll();