[clsi] use cheapest gzip compression level for history snapshot (#32251)
memoir manual with 1.5MiB snapshot:
level |load/decompress time | store/compress time | size | ratio | total sync time
--- | --- | --- | --- | --- | ---
6 | 18ms | 57ms | 412KiB | 26% | 88ms
1 | 17ms | 28ms | 509KiB | 32% | 53ms
0 | 8ms | 10ms | 1578KiB | 0% | 33ms
total sync: read snapshot, walk dir, sync files to disk, save snapshot
GitOrigin-RevId: a2b1ee063af5aa749014f942db5e08bb1e685848