Migrate deletion adjourned period after admin settings revamp

Problem to solve

With the changes in !86568 (merged) the deletion_adjourned_period can no longer be 0.

See the discussion !86568 (comment 965510842) for more context.

Suggested solution

Add a migration to update the deletion_adjourned_period to 1 where it is 0.

Implementation

1. Add a database migration.

ApplicationSetting.where(deletion_adjourned_period: 0).update_all(deletion_adjourned_period: 1)

2. Remove the update_deletion_adjourned_period before validation hook that was temporarily used to update the period to 1.