/series/add: disable country suggestion when country has been specified

[php-coder]

We shouldn't try to suggest a country when user has already specified it in URL (e.g. /series/add?country=italy).

Tech debt for: 9827abb (#517)

[php-coder]

@Shkarin I fixed it with a bit Thymeleaf magick! :)

[Shkarin]

Что-то не помогло

[php-coder]

Не в тот issue ответил или правда не помогло?