game_list: Use RegisteredCacheUnion for installed

Reduces code

src/core/crypto/ctr_encryption_layer.cpp

@@ -21,7 +21,7 @@ size_t CTREncryptionLayer::Read(u8* data, size_t length, size_t offset) const {
         UpdateIV(base_offset + offset);
         std::vector<u8> raw = base->ReadBytes(length, offset);
         cipher.Transcode(raw.data(), raw.size(), data, Op::Decrypt);
-        return raw.size();
+        return length;
     }
 
     // offset does not fall on block boundary (0x10)

src/yuzu/game_list.cpp

@@ -621,9 +621,7 @@ void GameListWorker::run() {
     stop_processing = false;
     watch_list.append(dir_path);
     FillControlMap(dir_path.toStdString());
-    AddInstalledTitlesToGameList(Service::FileSystem::GetUserNANDContents());
+    AddInstalledTitlesToGameList();
-    AddInstalledTitlesToGameList(Service::FileSystem::GetSystemNANDContents());
-    AddInstalledTitlesToGameList(Service::FileSystem::GetSDMCContents());
     AddFstEntriesToGameList(dir_path.toStdString(), deep_scan ? 256 : 0);
     nca_control_map.clear();
     emit Finished(watch_list);

src/yuzu/game_list_p.h

@@ -239,7 +239,7 @@ private:
     const std::unordered_map<std::string, std::pair<QString, QString>>& compatibility_list;
     std::atomic_bool stop_processing;
 
-    void AddInstalledTitlesToGameList(std::shared_ptr<FileSys::RegisteredCache> cache);
+    void AddInstalledTitlesToGameList();
     void FillControlMap(const std::string& dir_path);
     void AddFstEntriesToGameList(const std::string& dir_path, unsigned int recursion = 0);
 };