Remove the skip_notification attribute from Member

Now that we use NullNotificationService for LDAP users, this attribute
is no longer necessary.

app/models/members/group_member.rb

@@ -44,33 +44,33 @@ class GroupMember < Member
   private
 
   def send_invite
-    run_after_commit_or_now { notification_service.invite_group_member(self, @raw_invite_token) } unless @skip_notification
+    run_after_commit_or_now { notification_service.invite_group_member(self, @raw_invite_token) }
 
     super
   end
 
   def post_create_hook
-    run_after_commit_or_now { notification_service.new_group_member(self) } unless @skip_notification
+    run_after_commit_or_now { notification_service.new_group_member(self) }
 
     super
   end
 
   def post_update_hook
     if access_level_changed?
-      run_after_commit { notification_service.update_group_member(self) } unless @skip_notification
+      run_after_commit { notification_service.update_group_member(self) }
     end
 
     super
   end
 
   def after_accept_invite
-    notification_service.accept_group_invite(self) unless @skip_notification
+    notification_service.accept_group_invite(self)
 
     super
   end
 
   def after_decline_invite
-    notification_service.decline_group_invite(self) unless @skip_notification
+    notification_service.decline_group_invite(self)
 
     super
   end

app/models/members/project_member.rb

@@ -101,7 +101,7 @@ class ProjectMember < Member
   end
 
   def send_invite
-    run_after_commit_or_now { notification_service.invite_project_member(self, @raw_invite_token) } unless @skip_notification
+    run_after_commit_or_now { notification_service.invite_project_member(self, @raw_invite_token) }
 
     super
   end
@@ -109,7 +109,7 @@ class ProjectMember < Member
   def post_create_hook
     unless owner?
       event_service.join_project(self.project, self.user)
-      run_after_commit_or_now { notification_service.new_project_member(self) } unless @skip_notification
+      run_after_commit_or_now { notification_service.new_project_member(self) }
     end
 
     super
@@ -117,7 +117,7 @@ class ProjectMember < Member
 
   def post_update_hook
     if access_level_changed?
-      run_after_commit { notification_service.update_project_member(self) } unless @skip_notification
+      run_after_commit { notification_service.update_project_member(self) }
     end
 
     super
@@ -134,13 +134,13 @@ class ProjectMember < Member
   end
 
   def after_accept_invite
-    notification_service.accept_project_invite(self) unless @skip_notification
+    notification_service.accept_project_invite(self)
 
     super
   end
 
   def after_decline_invite
-    notification_service.decline_project_invite(self) unless @skip_notification
+    notification_service.decline_project_invite(self)
 
     super
   end

ee/app/models/ee/member.rb

@@ -5,8 +5,6 @@ module EE
     extend ActiveSupport::Concern
     extend ::Gitlab::Utils::Override
 
-    attr_accessor :skip_notification
-
     class_methods do
       extend ::Gitlab::Utils::Override
 
@@ -15,7 +13,6 @@ module EE
         super
 
         member.attributes = {
-          skip_notification: ldap,
           ldap: ldap
         }
       end