This is the first phase of providing strong exception safety guarantees by the generic `compaction_backlog_tracker::replace_sstables`.
Once all compaction strategies backlog trackers' replace_sstables provide strong exception safety guarantees (i.e. they may throw an exception but must revert on error any intermediate changes they made to restore the tracker to the pre-update state).
Once this series is merged and ICS replace_sstables is also made strongly exception safe (using infrastructure from size_tiered_backlog_tracker introduced here), `compaction_backlog_tracker::replace_sstables` may allow exceptions to propagate back to the caller rather than disabling the backlog tracker on errors.
Closes#14104
* github.com:scylladb/scylladb:
leveled_compaction_backlog_tracker: replace_sstables: provide strong exception safety guarantees
time_window_backlog_tracker: replace_sstables: provide strong exception safety guarantees
size_tiered_backlog_tracker: replace_sstables: provide strong exception safety guarantees
size_tiered_backlog_tracker: provide static calculate_sstables_backlog_contribution
size_tiered_backlog_tracker: make log4 helper static
size_tiered_backlog_tracker: define struct sstables_backlog_contribution
size_tiered_backlog_tracker: update_sstables: update total_bytes only if set changed
compaction_backlog_tracker: replace_sstables: pass old and new sstables vectors by ref
compaction_backlog_tracker: replace_sstables: add FIXME comments about strong exception safety
bfaac3a239