Fix duplicate backfill CANCELING status check (dagster-io#23077)

Summary:
From the comment it looks like this was supposed to be CANCELED? There
is already a CANCELING check above, so this code would never run.

Test Plan: BK

## Summary & Motivation

## How I Tested These Changes

python_modules/dagster/dagster/_core/execution/asset_backfill.py

@@ -1125,7 +1125,7 @@ def execute_asset_backfill_iteration(
  logger.debug(
  f"Updated asset backfill data after cancellation iteration: {updated_asset_backfill_data}"
  )
- elif backfill.status == BulkActionStatus.CANCELING:
+ elif backfill.status == BulkActionStatus.CANCELED:
  # The backfill was forcibly canceled, skip iteration
  pass
  else: