Drop encrypted_ai_access_token(_iv) from AppSettings

Second attempt after the corrective action:
previously, we had wrong ignore rule in the model.

db/post_migrate/20240116131144_remove_application_settings_ai_access_token_column_corrected.rb

+# frozen_string_literal: true
+
+class RemoveApplicationSettingsAiAccessTokenColumnCorrected < Gitlab::Database::Migration[2.2]
+  milestone '16.9'
+
+  def up
+    remove_column :application_settings, :encrypted_ai_access_token, if_exists: true
+    remove_column :application_settings, :encrypted_ai_access_token_iv, if_exists: true
+  end
+
+  def down
+    add_column :application_settings, :encrypted_ai_access_token, :binary, if_not_exists: true
+    add_column :application_settings, :encrypted_ai_access_token_iv, :binary, if_not_exists: true
+  end
+end

db/schema_migrations/20240116131144

+f10ce3c873e430283102232bf1830eda9a746b42862566500e05f6725988a21d
\ No newline at end of file

db/structure.sql

@@ -12584,8 +12584,6 @@ CREATE TABLE application_settings (
     wiki_asciidoc_allow_uri_includes boolean DEFAULT false NOT NULL,
     namespace_aggregation_schedule_lease_duration_in_seconds integer DEFAULT 300 NOT NULL,
     container_registry_data_repair_detail_worker_max_concurrency integer DEFAULT 2 NOT NULL,
-    encrypted_ai_access_token bytea,
-    encrypted_ai_access_token_iv bytea,
     vertex_ai_host text,
     encrypted_vertex_ai_credentials bytea,
     encrypted_vertex_ai_credentials_iv bytea,