Simplify implementation by removing some unused code

Only applies to cauldron loader which doesn't exist on Modrinth or
CurseForge, and doesn't even make sense for shaders.

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

launcher/ui/dialogs/ReviewMessageBox.h

@@ -16,7 +16,6 @@ class ReviewMessageBox : public QDialog {
     using ResourceInformation = struct res_info {
         QString name;
         QString filename;
-        QString custom_file_path{};
         QString provider;
         QStringList required_by;
         QString version_type;