Fix 2.7 warnings related to attr_encrypted

Currently, attr_encrypted gem implements dirty attrs
without handling kwargs properly.

If we just replace using attr_changed? method with
calling attribute_changed?(attr), it fixes the warning

It allows us getting away without updating the gem

app/models/alert_management/http_integration.rb

@@ -52,6 +52,10 @@ module AlertManagement
       endpoint_identifier == LEGACY_IDENTIFIER
     end
 
+    def token_changed?
+      attribute_changed?(:token)
+    end
+
     # Blank token assignment triggers token reset
     def prevent_token_assignment
       if token.present? && token_changed?

app/models/clusters/platforms/kubernetes.rb

@@ -247,7 +247,7 @@ module Clusters
       def prevent_modification
         return if provided_by_user?
 
-        if api_url_changed? || token_changed? || ca_pem_changed?
+        if api_url_changed? || attribute_changed?(:token) || ca_pem_changed?
           errors.add(:base, _('Cannot modify managed Kubernetes cluster'))
           return false
         end

app/models/pages_domain.rb

@@ -188,7 +188,7 @@ class PagesDomain < ApplicationRecord
 
   def user_provided_key=(key)
     self.key = key
-    self.certificate_source = 'user_provided' if key_changed?
+    self.certificate_source = 'user_provided' if attribute_changed?(:key)
   end
 
   def user_provided_certificate
@@ -207,7 +207,7 @@ class PagesDomain < ApplicationRecord
 
   def gitlab_provided_key=(key)
     self.key = key
-    self.certificate_source = 'gitlab_provided' if key_changed?
+    self.certificate_source = 'gitlab_provided' if attribute_changed?(:key)
   end
 
   def pages_virtual_domain

app/models/project_services/alerts_service_data.rb

@@ -11,4 +11,8 @@ class AlertsServiceData < ApplicationRecord
     mode: :per_attribute_iv,
     key: Settings.attr_encrypted_db_key_base_truncated,
     algorithm: 'aes-256-gcm'
+
+  def token_changed?
+    attribute_changed?(:token)
+  end
 end

app/models/remote_mirror.rb

@@ -308,7 +308,7 @@ class RemoteMirror < ApplicationRecord
   end
 
   def mirror_url_changed?
-    url_changed? || credentials_changed?
+    url_changed? || attribute_changed?(:credentials)
   end
 
   def saved_change_to_mirror_url?