Update _charge_id in metadata (#4131)

* If _charge_id does not exist, update it. This happens on some sites
where maybe_process_upe_redirect does not run, but payment has completed
correctly.

Co-authored-by: Jessy P <jessy.pappachan@automattic.com>

changelog/fix-3857-update-charge-id

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fix
+
+update _charge_id metadata to fix Refund button

includes/class-wc-payments-webhook-processing-service.php

@@ -350,6 +350,11 @@ private function process_webhook_payment_intent_succeeded( $event_body ) {
 		$charges_data  = $this->read_webhook_property( $event_charges, 'data' );
 		$charge_id     = $this->read_webhook_property( $charges_data[0], 'id' );
 
+		// update _charge_id meta if it doesn't exist - happens when maybe_process_upe_redirect fails sometimes.
+		if ( $charge_id && ! $order->get_meta( '_charge_id' ) ) {
+			$order->update_meta_data( '_charge_id', $charge_id );
+		}
+
 		$this->order_service->mark_payment_completed( $order, $intent_id, $intent_status, $charge_id );
 
 		// Send the customer a card reader receipt if it's an in person payment type.