Fixed: Use Nzb title as scene name when available

- Use Nzb title as scene name when available
- Only use file name as scene name when its highly likely that it's an actual scene name
- Don't store `DRONE` as default release group in the DB
- Clean up the db removing obviously wrong scene names


Is it an idea to add an additional Execute.WithConnection to search for related grabbed events and fill in the scenename based on the original nzb name?