perf(sessions): skip excluded metadata during cleanup (#138470)

perf(sessions): skip excluded metadata during cleanup (#138470)

Filter safe excluded keys before SQLite metadata projection while preserving
exact returned-key membership across supported Node and SQLite encodings.
Keep the original query for empty exclusions and preserve embedded NUL in
the existing bound string-set helper.

Cover excluded-row acquisition, survivor/corruption semantics, text encoding,
and helper binding without changing schema, indexes, or retention policy.