Simplify customer code

The API endpoint merges the created_manually flag in the params already.
No need to write it separately.

app/controllers/api/v1/customers_controller.rb

@@ -31,7 +31,6 @@ module Api
         authorize! :update, Enterprise.find(customer_params[:enterprise_id])
         customer = Customer.find_or_new(customer_params[:email], customer_params[:enterprise_id])
         customer.assign_attributes(customer_params)
-        customer.set_created_manually_flag
 
         if customer.save
           render json: Api::V1::CustomerSerializer.new(customer), status: :created

app/models/customer.rb

@@ -54,13 +54,6 @@ class Customer < ApplicationRecord
     "#{first_name} #{last_name}".strip
   end
 
-  def set_created_manually_flag
-    self.created_manually = true
-    return unless persisted?
-
-    update_attribute(:created_manually, true)
-  end
-
   private
 
   def downcase_email

spec/requests/api/v1/customers_spec.rb

@@ -190,6 +190,9 @@ describe "Customers", type: :request do
             allow_charges: false,
             terms_and_conditions_accepted_at: nil,
           )
+
+          customer = Customer.find(json_response[:data][:attributes][:id])
+          expect(customer.created_manually).to eq true
         end
       end