Create the code after_create to ensure it rolls back the transaction if the code fails

This is really an edge case, but because of that in the unlikely case it happens we're better off erroring and fixing it.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: danhalson

app/models/school.rb

@@ -52,7 +52,7 @@ class School < ApplicationRecord
   before_save :format_uk_postal_code, if: :should_format_uk_postal_code?
 
   # TODO: Remove the conditional once the feature flag is retired
-  after_commit :generate_code!, on: :create, if: -> { FeatureFlags.immediate_school_onboarding? }
+  after_create :generate_code!, if: -> { FeatureFlags.immediate_school_onboarding? }
 
   def self.find_for_user!(user)
     school = Role.find_by(user_id: user.id)&.school || find_by(creator_id: user.id)