## Problem
Various places in remote storage were not subject to a timeout (thereby
stuck TCP connections could hold things up), and did not respect a
cancellation token (so things like timeline deletion or tenant detach
would have to wait arbitrarily long).
## Summary of changes
- Add download_cancellable and upload_cancellable helpers, and use them
in all the places we wait for remote storage operations (with the
exception of initdb downloads, where it would not have been safe).
- Add a cancellation token arg to `download_retry`.
- Use cancellation token args in various places that were missing one
per #5066Closes: #5066
Why is this only "basic" handling?
- Doesn't express difference between shutdown and errors in return
types, to avoid refactoring all the places that use an anyhow::Error
(these should all eventually return a more structured error type)
- Implements timeouts on top of remote storage, rather than within it:
this means that operations hitting their timeout will lose their
semaphore permit and thereby go to the back of the queue for their
retry.
- Doing a nicer job is tracked in
https://github.com/neondatabase/neon/issues/6096
this will make it easier to test if an added allowed_error does in fact
match for example against a log file from an allure report.
```
$ python3 test_runner/fixtures/pageserver/allowed_errors.py --help
usage: allowed_errors.py [-h] [-i INPUT]
check input against pageserver global allowed_errors
optional arguments:
-h, --help show this help message and exit
-i INPUT, --input INPUT
Pageserver logs file. Reads from stdin if no file is provided.
```
Co-authored-by: Alexander Bayandin <alexander@neon.tech>
