misc(fee): Delete zero amount finalized fees (#3020)

## Description

This PR removes the charge fees attached to finalized or voided invoices
and having `amount = 0`.

In a close future, these fees will not be generated anymore, and the
logic built around it will be refactored (adjusted fees, daily_usage
computation...)

db/migrate/20250103124802_drop_zero_amount_fees.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+class DropZeroAmountFees < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  class FeesTax < ApplicationRecord; end
+
+  class Fee < ApplicationRecord; end
+
+  def change
+    sql = <<~SQL
+      SELECT fees.id FROM fees
+      INNER JOIN invoices ON fees.invoice_id = invoices.id
+      INNER JOIN organizations ON invoices.organization_id = organizations.id
+      WHERE
+        invoices.status IN (1, 2, 6) -- finalized, voided and closed
+        AND fees.fee_type = 0 -- charge
+        AND fees.amount_cents = 0
+        AND fees.units = 0
+        AND fees.pay_in_advance = false
+        AND fees.true_up_parent_fee_id IS NULL
+        AND fees.id NOT IN (
+          SELECT f.true_up_parent_fee_id
+          FROM fees f
+          WHERE f.true_up_parent_fee_id IS NOT NULL
+        )
+        AND fees.id NOT IN (
+          SELECT fee_id
+          FROM adjusted_fees
+          WHERE adjusted_fees.fee_id IS NOT NULL
+        )
+        AND NOT ('zero_amount_fees' = ANY(organizations.premium_integrations))
+        LIMIT 1000
+    SQL
+
+    while (ids = ActiveRecord::Base.connection.select_all(sql).rows.map(&:first)).any?
+      FeesTax.where(fee_id: ids).delete_all
+      Fee.where(id: ids).delete_all
+
+      puts "Deleted #{ids.size} fees - #{Time.current.iso8601}" # rubocop:disable Rails/Output
+    end
+  end
+end