Severity: medium
fmt::format("{}", ks_names_set) in a ternary expression eagerly
formats an unordered_set<sstring> even when debug logging is disabled.
Use seastar::value_of() to defer the formatting to log-time.
AI-assisted: OpenCode / Claude Opus 4.6
Signed-off-by: Yaniv Kaul <yaniv.kaul@scylladb.com>