Test suite: identify and document race conditions
_Originally created by Tails on [#5330 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/5330)_
Updated scope of this ticket: https://gitlab.tails.boum.org/tails/tails/-/issues/5330#note_117537.
A `sleep` that’s good enough on your hardware might not be good enough
on mine (or in a nested VM setup in particular). We need to, whenever
possible, use reliable ways to detect the state we are waiting for
instead of `sleep`:ing some fixed time and hoping we’ve reached that
state by then.
Just run `git grep sleep features/step_definitions/*.rb` for an
up-to-date list of these "violations\".
Feature Branch: kytv/test/5330-race-conditions
Parent Task: tails/tails#8539
### Subtasks
- [x] tails/tails#5632
- [x] tails/tails#8742
- [x] tails/tails#9258
- [x] tails/tails#9877
### Related issues
- **Related to** tails/tails#10222
- **Related to** tails/tails#9330
issue