Remove unnecessary writes on customer creation

The form only submits enterprise id and email address. We don't need to
assign any other attributes.

app/controllers/admin/customers_controller.rb

@@ -37,10 +37,9 @@ module Admin
 
     def create
       @customer = Customer.find_or_new(customer_params[:email], customer_params[:enterprise_id])
-      @customer.assign_attributes(customer_params)
 
       if user_can_create_customer?
-        @customer.set_created_manually_flag
+        @customer.created_manually = true
         if @customer.save
           tag_rule_mapping = TagRule.mapping_for(Enterprise.where(id: @customer.enterprise))
           render_as_json @customer, tag_rule_mapping: tag_rule_mapping