Endless automatic upgrades
_Originally created by @anonym on [#11131 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/11131)_
Currently automatic upgrades have the limitation that only some N number
of them can be performed in a row before the system partition runs out
of space and automatic upgrades cannot be done further, but a full,
manual upgrade is needed. Ideally, automatic upgrades should be possible
forever, which will improve the UX and eliminate the recurring need to
manually verify the Tails ISO when doing these unavoidable full
upgrades.
Blueprint: https://tails.boum.org/blueprint/Endless_upgrades/
Feature Branch: feature/11131-endless-upgrade, iuk:feature/11131-endless-upgrade, perl5lib:feature/11131-endless-upgrade
### Subtasks
- [x] tails/tails#8534
### Related issues
- **Related to** tails/tails#7499
- **Related to** tails/tails#10478
- **Related to** tails/tails#11627
- **Related to** tails/tails#12392
- **Related to** tails/tails#15281
issue