this series silences the warnings from GCC 13. some of these changes are considered as critical fixes, and posted separately.
see also #13243Closes#13723
* github.com:scylladb/scylladb:
cdc: initialize an optional using its value type
compaction: disambiguate type name
db: schema_tables: drop unused variable
reader_concurrency_semaphore: fix signed/unsigned comparision
locator: topology: disambiguate type names
raft: disambiguate promise name in raft::awaited_conf_changes