Lists successful Helios backup runs in S3 using restore configuration.
Only runs with success status are returned. When run_location is omitted,
direct run directories under the configured restore path are listed,
newest first. If no restore path is configured, runs are listed from
the bucket root. Nested runs are not included in listing. When
run_location is provided, the full path from the bucket root through
the timestamp run directory is used for an exact lookup, returning zero
or one run.