Scale processing of "on-success", "on-error" and "on-complete" for Mistral

When it comes to processing big "on-success", "on-error" and "on-complete" clauses of direct Mistral workflows, Mistral doesn't scale it which leads to having one engine busy for a long time (sometimes ~ maximum duration of a DB transaction) while others not doing anything. In order to fix this problem, we may try ...