stop() methods, like destructors must always succeed,
and returning errors from them is futile as there is
nothing else we can do with them by continue with shutdown.
stop_ongoing_compactions, in particular, currently returns the status
of stopped compaction tasks from `stop_tasks`, but still all tasks
must be stopped after it, even if they failed, so assert that
and ignore the errors.
Fixes scylladb/scylladb#21159
* Needs backport to 6.2 and 6.1, as commit 8cc99973eb causes handles storage that might cause compaction tasks to fail and eventually terminate on shudown when the exceptions are thrown in noexcept context in the deferred stop destructor body
(cherry picked from commit e942c074f2)
(cherry picked from commit d8500472b3)
(cherry picked from commit c08ba8af68)
(cherry picked from commit a7a55298ea)
(cherry picked from commit 6cce67bec8)
Refs #21299Closesscylladb/scylladb#21434
* github.com:scylladb/scylladb:
compaction_manager: stop: await _stop_future if engaged
compaction_manager: really_do_stop: assert that no tasks are left behind
compaction_manager: stop_tasks, stop_ongoing_compactions: ignore errors
compaction/compaction_manager: stop_tasks(): unlink stopped tasks
compaction/compaction_manager: make _tasks an intrusive list
548170fb68