Remove uneccesary save when setting notification settings on user

These methods should behave as the rest of setters on
ActiveRecords, ergo setting the model state, but not saving it.

The save is called at the end of the action inside the controller
anyway, so this save is redundant.

app/models/user.rb

@@ -431,7 +431,6 @@ class User < ApplicationRecord
     define_method("#{name}=") do |value|
       attr_name = name.gsub('_notification', '').to_sym
       notifications_settings[attr_name] = value
-      save
     end
   end