@Sergey Krulikovskiy , thank you for posting this question. The update also contains the following line:
Recommended action
- Rewrite your existing multi-step web tests as custom availability tests before 31 August 2024.
[Update 07/12] as updated by Courtland in the reply, you will be able to update existing tests till August 31st, 2024. If this changes, the product team will send out a notice and update.
Hope this helps.