before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.
in this change, we define formatters for
* bound_kind_m
* sstable_state
* indexable_element
* deletion_time
drop their operator<<:s
Refs #13245Closesscylladb/scylladb#17490
* github.com:scylladb/scylladb:
sstables: add fmt::formatter for deletion_time
sstable: add fmt::formatter for indexable_element
sstables: add fmt::foramtter for sstable_state
sstables: add fmt::formatter for sstables::bound_kind_m