Fix performance regression in Account::Field#verifiable? (mastodon#8719)

* Fix performance regression in Account::Field#verifiable?

Regression from mastodon#8703

* Fix code style issue

Author: Gargron

app/models/account.rb

@@ -323,7 +323,7 @@ def verified?
     end
 
     def verifiable?
-      value.present? && /\A#{FetchLinkCardService::URL_PATTERN}\z/ =~ value
+      value.present? && value.start_with?('http://', 'https://')
     end
 
     def mark_verified!