You should be able to avoid modifying JSON and having to go find some automatically generated uuid in this step: We then created the index pattern for this "logstash_test_metrics"
Your saved search has always referenced the index pattern by id, but the id was the name of the index pattern originally. Now, when you are filling out the form to create the index pattern, expand the "advanced options" toggle, which will show you the field for specifying a custom id, and use "logstash_test_metrics" as your id.