pipewire-object-mixin: make sure enum params task is only triggered once

Always remove the task from the list before returning to make sure it will
always be triggered once.
2 jobs for tasks-fix in 1 minute and 7 seconds
Status Job ID Name Coverage
  Container
passed container_fedora #9896761

00:00:27

 
  Build
passed build_on_fedora #9896762

00:00:39