Ensure right tasks dropped down when toggling 'show all tasks'

There is also a bug that I have found:
1. Drop down a task
2. Select `Show historic tasks`
3. The task that has been dropped down changes

It looks like which is dropped down is tied to index rather than task. I don't think this is a massive bug so if you want to spin it into a new issue then go for it

_Originally posted by @DominicOram in https://github.com/DiamondLightSource/atlas/pull/104#pullrequestreview-4704052999_

Reproduce the issue by expanding a task and selecting “Show historic tasks” in the task list UI. Trace how the expanded task is identified when the list changes, then verify that the same task remains expanded after toggling the option. Add or update a regression test if the project has coverage for this interaction.

Written by the indexing model from the issue text.