This article walks you through how you can trigger the execution after the pipeline execution failed.
As you know whenever workflow fails in the pipeline it will roll back.
So you can put your all the functionality of what would represent a workflow, in the rollback steps of an initial workflow which failed in the pipeline. As marked in the below image:
Setup up the dependent workflow you would want to run on failure.
Make a manual trigger for it and select type as webhook and Payload Type* as Custom (Shown in Image Below):
Then use the resulting manual trigger values (either as rest API or curl) and call it on rollback of the failed workflow, either as a shell script (as curl) or HTTP step as post.
Hope this article helps you out.