Do not flag www redirection in redirection check

Related issues
https://github.com/AdguardTeam/DeadDomainsLinter/issues/27
https://github.com/AdguardTeam/DeadDomainsLinter/issues/16
In checking the removed rules which are actually still useful, I noticed many of them have www redirect i.e. redirect to `www.(the accessed domain)` when accessed without `www`. This is a special case and should not be flagged in the check as with the case of https://github.com/AdguardTeam/DeadDomainsLinter/issues/16.

An example is `fxstreet.it` removed by https://github.com/AdguardTeam/AdguardFilters/commit/f2ae31e421ebae9dbe6f55669a9bf075f181dafd#diff-d1dd04144f2bef00096914d94854149276775e06d422b144faea333f69bfb0de Somehow only `.it` is low-traffic, hence probably not in the DNS data, but anyway the site is living and the rule is still active.