[Fleet] Unenroll action is stuck in progress after force unenroll agent

[juliaElastic]

Related to #140267
There is a bug of unenroll action stuck in "in progress" state after force unenrolling the same agents.
Should we clean somehow the unenroll action when the user force unenroll an agent?

Here I unenrolled an offline agent, then force unenrolled and the UI is stuck with "In progress" status:

As a solution, the force unenroll logic could check if there is a pending unenroll action for the same agent(s), and write the action results to ES, so that the action would move to completed status in Agent activity.

Originally posted by @nchaulet in #140510 (comment)

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[kpollich]

As a solution, the force unenroll logic could check if there is a pending unenroll action for the same agent(s), and write the action results to ES, so that the action would move to completed status in Agent activity.

This sounds like a viable path forward to me. The "force" nature of this action seems to me like it'd be okay for us to make manual edits to the action status throughout the process. I'm +1 on this approach.